CLINTON, Iowa — Amid new criticisms about his Senate attendance record, Marco Rubio said some of his rival candidates are getting “a little desperate and a little nasty.”

The Florida senator kicked off an Iowa tour Tuesday, as a super political action committee backing Jeb Bush announced a new ad in the state accusing Rubio of missing a Senate meeting after the November terrorist attacks in Paris. New Jersey Gov. Chris Christie also piled on during an Iowa stop, questioning Rubio’s Senate attendance.

After a town hall meeting in the leadoff caucus state, Rubio said the ad from Right to Rise “isn’t accurate,” adding that as a member of the Senate Intelligence Committee he attended a different briefing on the Paris attacks. Asked about Christie’s comments, he said the governor had been away from New Jersey “half the time.”

“Candidates I think as we get down the stretch here some of them get a little desperate and a little nasty in their attacks,” Rubio said.

Rivals have tried to make an issue of Rubio’s attendance in the Senate. In 2015, he has missed about 35 percent of roll call votes, according to GovTrack.us. That’s more than any of the other senators running for president.

But several Iowa attendees said they were not troubled by Rubio’s Senate record.

“He’s out here trying to get the popular vote of the people,” said Mary Reed, 65, of Bellevue, Iowa, who is considering supporting Rubio “Missing a few votes does not bother me.

Before over 125 people in Clinton, Iowa, Rubio — who was joined by his family and Rep. Trey Gowdy, of South Carolina — kept his remarks focused on President Barack Obama and Democratic front-runner Hillary Clinton, rather than his Republican counterparts.

“I have lived many of the things that people face,” Rubio said. “I want to know how Hillary Clinton is going to lecture me about people living paycheck to paycheck. I grew up paycheck to paycheck.”

Rubio stressed his support for securing the borders, investing in the military and repealing the Affordable Care Act. He also said he would back a convention of the states to amend the U.S. Constitution, to pass amendments dealing with term limits and a balanced budget. Conservative groups have been pushing for such an event, which has never happened since the original convention in 1787. Rubio said he supported a convention limited to those two topics.

Rubio is wrapping up his year in Iowa, where the Feb. 1 caucuses will kick off presidential voting, but has tried to avoid prioritizing any one of the early voting states, by running a nationally focused campaign that leans on strong debate performances and television advertising.

Unlike Texas Sen. Ted Cruz, who has set his sights on Iowa, or former Florida Gov. Jeb Bush, who is pushing hard in New Hampshire, Rubio continues to spread his time and money across the early states, showing no indication he will choose just one to make his mark.

While supporters say Rubio just needs to stay in the top cluster in the first few states, some see his approach as risky. But Rubio spokesman Alex Conant said the campaign has no plans to “give up on states we can win.”

In Iowa, recent polls have found Cruz and Donald Trump battling for first place, with Rubio usually a distant third. He’s seen as competing most directly with others considered part of the GOP establishment — Bush, New Jersey Gov. Chris Christie and Ohio Gov. John Kasich. Most agree he doesn’t actually need to win the caucuses, but must emerge as the establishment’s leader.

A good organization is important in Iowa because caucuses take more effort than a primary, requiring voters to show up at a fixed time on a winter night. The Republican caucuses drew about 120,000 voters in 2008 and 2012 — roughly 20 percent of registered Republicans.

Rubio has fewer paid staff than some competitors and his state director hails from Arkansas. He draws large, enthusiastic crowds and has done at least 49 public events in the state this year — more than Bush or Christie, but significantly fewer than Cruz, who has done at least 80.

Questions about Rubio’s organization efforts are echoed in other early voting states, including New Hampshire and South Carolina.