The self-described "joyful tortoise" in the race for the GOP presidential nomination is more angry than happy these days.
Former Florida Gov. Jeb Bush, who promised an optimistic campaign focused on his record rather than attacks on his rivals, has departed from that approach and begun to forcefully confront front-runner Donald Trump.
Just this week, Bush's campaign released a video and an online quiz targeted at Trump supporters that played up Trump's past support for abortion rights, universal healthcare and Democratic candidates, including front-runner Hillary Rodham Clinton. He also got personal, going after Trump's well-known phobia of germs.
"The man is not conservative," Bush told reporters in Miami on Tuesday. "Besides, he tries to personalize everything. If you're not totally in agreement with him, you're an idiot or stupid or don't have energy or blah blah blah."
That's a notable change in posture and tone for a candidate who is better known for his cerebral, wonky manner than his swagger. The shift is driven by Trump's relentless and personal needling of Bush, whom he described Thursday as "very low-energy person" and "a little bit sad," as well as Trump's unexpected and continuing dominance in the polls.
Trump goes after most of his Republican rivals, but seems to especially enjoy poking at Bush, whom he once hosted a fundraiser for at Trump Tower in Manhattan.
On Wednesday, Trump responded to Bush speaking Spanish at a news conference by telling Breitbart News, "He should really set the example by speaking English while in the United States." He has retweeted a critic who said Bush "has to like the Mexican Illegals because of his wife," who was born in Mexico.
Trump trolls Bush on social media, arguing that the candidate is ashamed of his last name and highlighting that his mother, former First Lady Barbara Bush, said in 2013 that the nation had had "enough Bushes" as president.
"Mother knows best, Jeb!" Trump said on that post, on Instagram. Trump's campaign did not respond to a request for comment.
Political observers say Bush was forced to act, both because of Trump's leading status and because of the sustained, personal nature of his attacks.
"At a certain point, you have to respond. Because if you don't, you look like you're a punching bag," said Tim Hagle, a political science professor at the University of Iowa. Bush has fallen to sixth place in an aggregate of recent polls in Iowa, the state that holds the first nominating contest in the nation.
Hagle noted that some of Bush's supporters had expressed concern over whether the wonky candidate, who hasn't run for office since 2002, could deal with the slashing nature of modern-day politics. "He's got to show he has some fight in him," Hagle said.
It's a question that dogged Bush's father, former President George H.W. Bush, noted Jack Pitney, a government professor at Claremont McKenna College and a former national GOP official. The nation's 41st president was the cover story of a 1987 Newsweek cover that said the then-vice president was "fighting the 'wimp factor.'"
"Now the younger Bush has to prove that he's not a wimp," Pitney said. The father fought back with pointed attacks on his rivals and the media, but Pitney questions whether that that is enough to tackle Trump because his draw for voters is based more on personality than his record. "I'm not sure that the attack on Trump's consistency is going to work. People are supporting him not because of consistency but because of brassiness."
Brassiness is not a quality that has ever been associated with Bush, who also lacks the Texas-twanged charisma of his brother, former President George W. Bush.
For much of the summer, Jeb Bush pointedly avoided showing antagonism. When asked about Trump by the media, Bush would respond, but he never brought up Trump himself, professing a lack of interest.
"I don't spend a lot of quality time going over the Trump message," Bush told the Daily Caller, a conservative publication, in July.
The new vigor -- for a candidate who has enviable advantages in fundraising but has floundered in the polls -- is purposeful and will continue, according to Bush campaign spokesman Tim Miller.
"Increasingly it has become clear that Trump was going to run a legitimate campaign so he's being treated as a legitimate candidate. Part of that is contrasting Gov. Bush's proven conservative record with Donald Trump's past as a New York liberal," Miller said. "This is going to be a sustained attack, a sustained campaign from Gov. Bush, to highlight the differences between him and Mr. Trump."
Bush's supporters appreciate the turn.
"In many ways, Donald Trump is a gift to Jeb Bush because he perfectly provides a very clear contrast to Jeb's record of conservative reform and accomplishment in Florida," said Paul Lindsay, spokesman for the Right to Rise USA super PAC, which has raised more than $100 million to back Bush's bid but is legally not allowed to coordinate with his effort. "The campaign is capitalizing on that, and rightly so."
The super PAC paid for an airplane to carry a banner reading "Trump 4 higher taxes. Jeb 4 Prez" over a Trump rally in Alabama in August but has focused its efforts on biographical television ads introducing Bush to early-state voters. Lindsay said that the group would not rule out future defensive action.
"We certainly reserve the right to defend Gov. Bush's record and contrast it with all the other candidates in the race, including Donald Trump," Lindsay said.
All of this sparring comes leading into the second GOP presidential debate Sept. 16 at the Reagan Library in Simi Valley. Moderators are likely to seize on the acrimony, as they tried to do unsuccessfully during an August debate. In that faceoff, Bush didn't tear into Trump, unlike some of his rivals, notably Kentucky Sen. Rand Paul. Bush's performance in that debate -- a former governor compared with a showman -- was widely panned.
"It's tough because it's a tactic Trump comes by naturally -- preternaturally -- and for Jeb, it's a learned reaction," said Reed Galen, a GOP strategist who worked for former President George W. Bush.
But given Bush's recent increased aggression, he may not have the option to try to sidestep Trump this time.
"He's painted himself into that corner," Galen said. "If he doesn't, then people will say he backed off and Trump may very well seize on that."