"Saturday night -- you didn't do too good," an elderly man told the 44-year-old senator. "But I'm still rooting for you."
Rubio smiled and said: "I feel good about it. We raised a lot of money online."
That's the way it's gone for Rubio since Saturday's debate here, where the freshman senator endured his toughest moment of a campaign season that has been remarkably mistake-free up until this point. He has had to reassure donors, voters and would-be supporters that he can steady the ship, unite the party and take on Democrats in the fall campaign when the pressure will be even more intense.
The plan now for the Rubio campaign comes down to this: Finish in the top tier of candidates in Tuesday's New Hampshire primary -- and bank on a strong showing in South Carolina and Nevada, where the campaign has quietly placed a heavy investment in TV ads and on the ground, to remain a formidable candidate heading into Super Tuesday in March. At the same time, his campaign is hoping that the governors in the race will underperform, helping him coalesce support and take the fight to Donald Trump.
The path may have gotten rougher after Saturday, when his decision to repeatedly use the same lines fed into criticism that the senator relies almost exclusively on rehearsed talking points, rather than his accomplishments in office.
Two senators who had been seriously weighing throwing their support behind Rubio privately told CNN that his debate performance had made them reassess the race until after the New Hampshire primary.
But coming to Rubio's aid Monday was the support of a Nebraska conservative senator, Deb Fischer, a sign that some in the party ranks were not ready to quit on the young Floridian just quite yet. And giving him cover with his base, Rush Limbaugh took to the airwaves to defend Rubio.
Still, Rubio is not finishing in New Hampshire the way he hoped. Addressing voters in Nashua early Monday, Rubio was surprisingly subdued, speaking in almost a monotone before a low-energy crowd at BAE Systems.
"You know, one of the things that's funny because people keep, in the press anyway, 'Why do you keep saying the same thing about Obama trying to change America?' I'm going to keep saying that a million times because I believe it's true."
There wasn't much of a response from the crowd.
When voters go to the polls here in the nation's first primary, Rubio's team is hoping that the candidate will emerge as the clear alternative to Trump, ending with a second place finish, and he'll be able to make a strong case to Republican voters that he can withstand a political storm in a general election. But if he ends up behind any of the governors in the race, possibly John Kasich or Jeb Bush, it could imperil Rubio's case that he's the lone candidate who can win the GOP nomination not named Trump or Ted Cruz.
The onslaught started after Saturday night when Rubio repeated on four separate occasions the same talking point asserting that Barack Obama had intended to "change" America, even after being called out by New Jersey Gov. Chris Christie. It only seemed to perpetuate the criticism that Rubio has accomplished little in his career other than the ability to give a good speech.
"When you repeat something over and over again, that's basically a canned phrase and it validates a belief you're not ready to be president," Bush told CNN's Dana Bash Monday.
Late Monday, Rubio got some good news when a CNN-WMUR poll found that he remained in second place, with 17%, compared to 31% for Trump, and Bush, Christie and Kasich far behind. Yet, a bulk of the poll's interviews were conducted before the debate, so it's impossible to know how Rubio's debate performance will affect his standing in the polls until Tuesday night.
"I think he was a bit rattled," Scott Douglas, an undecided voter in New Hampshire, said of Rubio's debate performance.
Rubio's campaign has done little to change its strategy since Saturday's debate. He has stuck religiously to his script -- as he has done for much of this campaign season -- rarely hewing off message. Some voters seem to like that.
At a coffee shop here in Nashua on Monday, a voter told Rubio: "I agree with you, I think Obama knows exactly what he's doing." Rubio responded: "I'm going to keep saying that."
Looking past New Hampshire
What the New Hampshire debate did was slow down the march towards Rubio, according to interviews with donors and GOP officials. It's still possible the party will unite behind him as the Trump alternative, but he still has his work cut out for him.
So Rubio is hedging his bets and trying to draw out his ample resources to stay in the race until mid-March, when the states begin to award delegates on a winner-take-all-basis, rather than proportionally.
In South Carolina, Rubio's campaign has spent $2.8 million on air -- with outside groups aligned with Rubio spending an additional $4.8 million on TV ads, according to the data tracking firm Kantar Media. The only group that has spent more is Right to Rise, the pro-Bush super PAC that has dropped nearly $10 million in the state, with many ads lashing Rubio.
In Nevada, Rubio's super PAC, Conservative Solutions PAC, has reserved more time than any other group ahead of the caucuses there later this month, with $461,000 of ad time booked. Only Rubio's campaign has spent money on TV, with a $123,000 ad buy showing Rubio attacking Hillary Clinton as "disqualified."
On Monday, Rubio sent signals that he was girding for a long campaign.
"We will do well here in New Hampshire and move on to South Carolina," Rubio said on CBS. "And when this process finishes in what is a very unusual election cycle, I feel very good about our chances to be the nominee."