While Super Tuesday left the Democrats with a pair of front-runners whom President Donald Trump believes he can define and defeat, there are still some private worries in the White House.

There is concern that the Democrats’ messy nomination contest may end up producing an emboldened version of the very man who once worried Trump so much as a foe that it led to the president’s impeachment. That would be Joe Biden.

Still, there was plenty for Trump to like in Tuesday’s 14-state round of voting that transformed the Democratic race into a delegate shootout between an avowed proponent of democratic socialism (Bernie Sanders) and a longtime Washington insider (Biden). It banished from the race former New York Mayor Mike Bloomberg, whose endless millions had gotten under the president’s skin, and it pushed aside Massachusetts Sen. Elizabeth Warren, who could have proved to be a formidable rhetorical challenger against Trump. That sets up Trump to run for reelection on familiar territory and allows him to revive some of the same lines of attack that proved successful in 2016.

The public reaction from Trump and his campaign on Wednesday was gleeful as Biden’s remarkable campaign comeback reset the Democratic nomination fight into a two-candidate contest with Sanders.

Those around the president have long asserted that Sanders, with his unapologetic support for “Medicare for All,” free college and other wish list items, is too liberal for most of the nation. They also believe Biden has lost a step and is saddled with a decadeslong Washington record and questions surrounding the conduct of his son Hunter. “Truly is a ’heads we win, tails they lose’ situation,” said Trump campaign communications director Tim Murtaugh.

But there are some caveats in the campaign’s confidence.

Trump and his team have spent the last year trying to lump the Democratic contenders together as left-wing radicals. Biden’s working-class appeal and more pragmatic policy approach aren’t a ready fit with that GOP framing. Trump allies have pointed to Biden’s embrace of liberal positions on gun control, but he steered clear of the more extreme positions of his rivals on health care.