WASHINGTON (Sinclair Broadcast Group) -- When Jeb Bush landed in McAllen, Texas Monday to visit the U.S./Mexico border, the memory of another 2016 Republican presidential candidate's trip to a Texas border town loomed large over the former Florida governor.
"I think it's great that he's going down to the border because I think he'll now find out that it's not an act of love," current frontrunner Donald Trump said on "Fox & Friends," referring to Bush's comments earlier this year that many illegal immigrants come to the U.S. out of love and commitment to their families.
"I was down on the border," Trump, who visited Laredo last month, continued. "It's rough, tough stuff. This is not love, this is other things going on and I think he'll probably be able to figure that out maybe."
"I'm not going to get into the issues of what he said and I said," Bush said when asked about Trump's comments at a press conference in McAllen, pivoting instead to criticize Trump's immigration policy. "The simple fact is that his proposal is unrealistic, it would cost hundreds of billions of dollars, it will violate people' civil liberties, it will create friction with our third largest trading partner that's not necessary, and I think he's wrong about this."
As Trump's large shadow spreads on the Republican primary process and some of his rivals adopt his positions, Bush attacked the billionaire head-on last week, striking a more confrontational tone than he has in the past.
"Mr. Trump doesn't have a proven conservative record. He was a Democrat longer in the last decade than he was a Republican. He has given more money to Democrats than he's given to Republicans," Bush said at a town hall in New Hampshire Wednesday, at the same time that Trump was holding a competing event 20 miles away.
Bush continued attacking Trump's conservative credentials on Thursday, highlighting his past liberal positions on several issues.
A super PAC supporting Bush flew a plane over a stadium where Trump was speaking to at least 20,000 people Friday night with a banner that read, "Trump 4 higher taxes. Jeb 4 Prez."
Strategists and experts say it is too soon to tell whether this represents a concerted shift in strategy for Bush, who was widely expected to be the frontrunner in the race, but it is not surprising that he is trying to stand out from the crowded Republican field by targeting Trump.
"I think that Trump's making all of them look pretty weak," Democratic strategist Craig Varoga said, although he cautioned, "they're making a mistake by trying to replicate his rhetoric and be Trump-like."
All of the candidates are trying to tap into the anger that is fueling a lot of Trump's support, according to Republican strategist Matt Mackowiak, and Bush may be showing some frustration that Trump seems to be judged by different rules.
"Trump has gone after Jeb pretty relentlessly for the last few weeks," Mackowiak said, and Bush remained mostly silent until last week, so it may have partially been a response to Trump scheduling the town hall directly against his in New Hampshire.
"Bush is not losing support to Trump," he said. Potential Bush supporters who do not like what he is saying will likely turn to one of the other establishment candidates, not Trump, so there may not be much to gain from an anti-Trump campaign.
"This could be Jeb saying what needs to be said," either to show energy or leadership, but his attacks--even the super PAC flying the banner over Trump's event--have been easy and inexpensive to do. If Bush or his supporters start spending money on negative ads against Trump, that will signal a real change in course.
Experts agree that it is hard to predict whether Bush's recent comments are indicative of a broader strategy on his part, and if so, whether taking on Trump will help him with primary voters.
"You don't always know what's a change in strategy for a candidate until you've seen a pattern establish itself over a period of time," said Dave Hopkins, a political science professor at Boston College.
"My sense is, in the grand scheme of things, probably Trump helps Jeb, at least at this point in the race," Hopkins said. Trump's presence keeps the other candidates from gaining much traction, but that has clearly not been enough to keep Bush on top in the polls.
"Certainly, Jeb's previous strategy of trying to coast through this period of the campaign as the favorite has been upended."
However, Hopkins said the risk of attacking Trump is that when one candidate in a multi-candidate race attacks another, both are generally damaged and the rest of the field benefits.
"That's part of why Trump's rise is so complicated for the rest of the candidates to respond to," he said.
Patrick Miller, a political science professor at the University of Kansas, said being more aggressive and taking Trump on directly could help Bush if he does it well.
"He needs to stand out and that's something that Jeb Bush has not done so far...He hasn't really built a strong brand in this election," Miller said, noting how effectively Trump has sold his brand to voters and taken ownership of the immigration issue.
"You have to wait until Trump really develops some vulnerabilities...You have to wait for him to stop being this new-fangled, shiny object," and attack his electability, Miller said. Going after Trump on immigration carries significant risks of either alienating Republican primary voters or general election voters by taking a stance that is seen as too extreme to the left or right.
"Any candidate right now needs to, if they're serious, not box themselves in on immigration."
Trump acknowledged Bush's criticism on Fox Monday, but he also took the opportunity to mock Bush, as he often does, as "low energy."
"Bush by the way attacked me in a very modest way. You know, he's a low energy person so when he attacks, he attacks with low energy."
Trump often boasts about how candidates Rick Perry and Lindsey Graham dropped in the polls after attacking him. Varoga, the Democratic strategist, said the mistake Trump's opponents, including Bush, are making is misunderstanding his appeal.
"It has to do with attitude and personality and Trump's willingness to shatter everything in his path...He's clearly proud of being a bull in a china shop," Varoga said.
According to Varoga, the candidates should be attacking Trump as "a narcissist who doesn't believe in anything," but Bush's approach so far makes him look afraid of his rival.
"Bush is hurt in the short term because he looks weak, and he's hurt in the long term because he looks desperate."
Trump continued his personal attack on Bush Monday afternoon, posting an Instagram video of an old interview clip where Bush's own mother says he should not run for president.
"I think it's a great country, there are a lot of great families, there are other people out there who are very qualified, and we've had enough Bushes," Barbara Bush says in the clip.
"Mother knows best Jeb!" the onscreen graphic reads.
Mackowiak said if Bush is going to go after Trump, he needs to be prepared for what Trump will throw back at him.
"He's got to do it well and he's got to stay committed to it" if he is going to adopt that strategy.
Bush received criticism last week after seemingly appropriating Trump's language and using the term "anchor babies" to describe children of undocumented immigrants. He snapped at a reporter Thursday who questioned his choice of the phrase, which is used frequently by Trump and considered offensive by many Hispanics.
Media reports noted that Bush was co-chairman of an organization advised Republican politicians not to use the term in a 2013 memo, something Trump seized upon on Twitter.
Bush's campaign told CNN he had no role in writing that memo and it was not signed.
The "anchor babies" issue derailed Bush's press conference for several minutes Monday. Bush called the suggestion that he used a derogatory term about immigrants "ludicrous" and explained that he was referring specifically to organized efforts that bring pregnant women, primarily Asians, to the U.S. solely to give birth to American citizens.
Echoing Trump again, Bush said, "I think we need to take a step back and chill out a little bit as it relates to the political correctness, that somehow you have to be scolded every time you say something."
Asked what term he would use to describe children of illegal immigrants instead, Bush seemed exasperated.
"You give me the name," he told a reporter. "You know, this so ridiculous. Give me the name that you want me to use and I'll use it."
Bush, whose campaign has launched a contest to win tickets to see his appearance on the first episode of Stephen Colbert's "Late Show," is in a stronger position than many of the lesser-known Republican candidates. He has name recognition and he has raised a lot of money already, which gives him a bit more freedom.
According to Miller, he should be able to stay in the race as the field whittles down in the fall and winter, but he still needs to build his brand and attacking Trump at times may be the best way to look conservative and aggressive.
"He can afford to wait things out until he thinks it's the right moment to speak or attack or act," Miller said.
Many of the other candidates are finding themselves in a predicament where they need media attention, but the only way to get that attention is to pick a fight with Trump or follow his lead. They may have initially hoped to wait it out until his candidacy collapsed as many predicted, but his resiliency eliminated that option.
"I don't know that anybody in either party has the luxury of ignoring this guy anymore," Varoga said.
While the dangers of attacking Trump and provoking his anger are well documented and have claimed the life of Lindsey Graham's cell phone, parroting his line carries risks of its own. Several candidates supported his position on ending birthright citizenship last week, but Scott Walker ended up contradicting himself with three different answers on the issue.
"'Me too' as a strategy is almost always ineffective. It makes them look like followers instead of making them look like strong potential presidents," Varoga said.
"They look like little 'me-too'-ers, shadows," Miller said, but Bush has largely tried to avoid that.
Hopkins said the challenge for the other candidates is that they want to be able to emerge as the more conservative alternative to Bush when Trump does falter, but the longer he gets all the attention, the more they risk getting lost in the shuffle.
"Trump has clearly shown the ability to sort of just dominate the press coverage and the popular interest in the race...and that's not likely to just go away tomorrow," he said.
When, or if, that domination will go away remains difficult to say, with Trump drawing support from about 25 percent of primary voters in polls and no events on the horizon that are likely to shake up that dynamic.
"The question is, is 25% Trump's ceiling?" Mackowiak said. With 17 candidates in the race, that is enough support to maintain a healthy lead, but as the field narrows, far more Republicans still oppose him than support him.
According to Varoga, who joked that he hates giving Republicans advice but said the country benefits from having two viable mainstream political parties, candidates chasing Trump to win over that 25% are only serving to marginalize their own party. Instead, they should be standing up for mainstream Republican values.
"By these people not challenging him, they're allowing him to become real...If unchallenged, he will become even more formidable," he said of the billionaire real estate developer.
"He is the classic developer who says that his project is the biggest and the best ever...He's running his campaign in exactly the same way" and they should be repudiating him and standing up for their party.
"I would ask what would Richard Nixon or Ronald Reagan do? Neither of those guys would have been afraid of Donald Trump," he said. They would not have followed Trump around like "schoolboys;" they would have confronted him directly.
"He's winning the swagger primary...In the absence of strong adults, a bombastic, swaggering billionaire will continue to hold center stage," Varoga said.
If the other candidates do not find an effective way to stand up against Trump rather than following his lead, Varoga said, he could become the party's nominee in 2016 despite his lack of conservative credentials or viable policy ideas.
"He's completely empty once you put his self-interest aside...God help us if the Republicans don't figure out a way to deal with this guy."
Mimicking Trump's position on immigration only serves to make him look like part of the Republican mainstream, according to Varoga, and that will be dangerous in the long run.
"Mainstreaming somebody like Donald Trump isn't only bad for the party, it's bad for the country."