With the New Hampshire primary poised to cut down the Republican field, candidates are sharpening their knives in a desperate bid for survival that on Thursday resembled a group attack on Sen. Marco Rubio, the freshman senator from Florida.
Then there is New Jersey Gov. Chris Christie, who seemed to be competing for a prize in aggressiveness, calling Rubio the "boy in the bubble" who is sheltered from tough questions and portraying him as too callow to serve as president.
Rubio's side took some shots of their own. In response to Cruz's charges about amnesty, the campaign said in a statement: "Cruz is lying. Marco opposes amnesty."
The intensity of the rhetoric is a sign of how much is riding on New Hampshire, the perception that Rubio is on the rise and the degree to which his rivals have a common interest in stopping him.
A strong showing by Rubio here could make him the main rival to Cruz, who finished first in the Iowa caucuses, and cripple efforts by Bush and Christie to consolidate establishment support.
By contrast, Donald Trump, still the leader in New Hampshire polls, has largely ignored Rubio. So too has Ohio Gov. John Kasich, who held his fire Thursday, even though he's staked his candidacy on New Hampshire. He demurred when given an opportunity to draw sharper contrasts with Rubio.
"This is the time now to be positive," he said.
Rubio, who finished third in the Iowa caucuses, is pitching himself to Republican voters as the only candidate who can unify the party and deliver them a victory in November's general election. Clinton is scared of him, he told a Manchester crowd Thursday.
"I give the party the best chance to win," Rubio said, eschewing criticism of his opponents in favor of broadsides against President Obama.
For his supporters, the attacks from other candidates are just proof that they're backing the right one.
"Everyone else is fighting among themselves," Debora Hallahan, 60, a nurse from Manchester who went to see the senator speak Thursday. "Marco Rubio goes straight to the issues."
An average of New Hampshire polls by the political website Real Clear Politics shows Rubio in second place, 20 percentage points behind Trump. Nipping at Rubio's heels is Cruz, followed by Kasich, Bush and Christie, in that order. Polls here can shift rapidly in the closing days of the campaign, however, particularly with multiple candidates in the field.
Poor outcomes in the Iowa caucuses already have ended the bids of three GOP candidates -- former Arkansas Gov. Mike Huckabee, former Pennsylvania Sen. Rick Santorum and Kentucky Sen. Rand Paul.
That still leaves nine Republican candidates, but New Hampshire probably will eliminate several of them.
Bush said he was prepared to continue his campaign in South Carolina, but he's also counting on New Hampshire to "reset" the primary battle and resucitate his flagging candidacy.
Christie is more publicly counting on New Hampshire, telling the Washington Post that he would have to reconsider his campaign if he doesn't beat his fellow governors, Kasich and Bush, in the state.
Kasich has held nearly 100 town halls in New Hampshire in hopes that his moderate brand of Republican politics will connect with voters.
Cruz doesn't have as much riding on the state as any of the three governors, but he has his own reasons for targeting Rubio.
"If he lets Marco get his legs underneath him, and becomes someone who mainstream conservatives can rally around, then this game is over financially," said Rick Wilson, a Republican strategist who has worked with a pro-Rubio super PAC.
Rubio's momentum is also a concern for Jeff Kuhner, a conservative talk show host from Boston who backs Cruz and introduced the Texas senator at a Nashua event Wednesday.
If Cruz and Trump keep fighting each other, and the governors keep fighting over the same slice of the moderate electorate, it creates an opportunity for the Florida senator, Kuhner said.
With everyone bleeding each other, he said, "Rubio and the establishment come up the middle."
For more on Campaign 2016, follow @ChrisMegerian
Times staff writers Mark Z. Barabak and Evan Halper contributed to this report.