Former Secretary of State Hillary Clinton flipped questions about her progressive credentials and attacked Vermont Sen. Bernie Sanders early in Thursday’s MSNBC Democratic debate, pointing out specific points in his record that show that he has a checkered history with some liberal causes, too. On one of the top issues of the 2016 campaign so far — immigration reform — she implied that he’s really not up to snuff with Democratic positions.

“We have differences, and honestly I think we should be taking about what we want to do for the country, but if we’re going to get into labels, I don’t think it was progressive to vote against the Brady Bill,” she said, referencing his opposition to gun control legislation in the past, before hitting him on immigration and other issues. “I don’t think it was progressive to vote against Ted Kennedy’s immigration reform.”

Indeed, Sanders’s vote against the late Sen. Edward Kennedy’s 2007 immigration reform bill has been a thorn in Sanders’ side. He said he voted against the bill because the guest worker visa quotas in it would drive down wages for low-income workers. At the time, and still today, he did not oppose a pathway to citizenship for undocumented immigrants, but the fact remains that he opposed an immigration bill that was favored by immigration activists.

That vote, and some of his rhetoric since on the issue, has resulted in praise from unlikely places. Some conservative leaders and anti-immigration activists have said recently that they like how Sanders talks about immigration. That includes Rep. Steve King, R-Iowa, a strong immigrant opponent, who said the Vermont senator has immigration views that are closer to his than even some other Republicans.

Still, the fact remains that Clinton and Sanders have very similar positions on immigration reform, including support a pathway to citizenship. They’ve even both hired undocumented immigrants on their campaigns.

Clinton appears to have found a formidable foe in Sanders, but she is still widely favored to win the Democratic nomination over the Vermont senator. That is at least in part due to her well-established connections within the Democratic Party that Sanders lacks. In the so-called endorsement primary that has historically been better at predicting nominees than polls, Clinton is by far and away the leader. The website Five Thirty-Eight has compiled endorsements that have traditionally been the most important — from House representatives, senators and governors — and assigns weighted points to each endorsement. Clinton’s current score is 466 compared to Sanders’s 2 (he only has endorsements from two representatives and none from fellow senators or state governors).

Much of the talk around Sanders comes from his strong polling in New Hampshire and his surprise near-tie in the Iowa caucuses Monday. He leads Clinton 56 percent to 37.8 percent in New Hampshire, and a strong showing there on Tuesday could theoretically build on his momentum. Clinton, however, leads in the next two nominating contests after New Hampshire, Nevada on Feb. 20 and then South Carolina on Feb. 27. She also leads with very comfortable margins. She is up 19.5 percent in Nevada and up 29.5 percent in South Carolina.