For most Americans, the unofficial arrival of summer with Memorial Day is a cause for celebration. But for newly elected presidents, it’s more often been a reason for dread. Sagging job approval ratings, unanticipated challenges at home and abroad and, above all, diminishing legislative momentum have been hallmarks of the first summer in office for recent presidents.

The dynamic has afflicted presidents of both parties. But the problem was especially acute for Bill Clinton and Barack Obama, the last two Democratic presidents, who arrived in Washington, like Biden, with extremely ambitious legislative wish lists. During their first summers, both Clinton and Obama found themselves sinking into legislative quagmires that sapped their public support and energized their opponents.

Biden has advantages Clinton and Obama did not: The economy is recovering faster today than it did for either of them, opponents have not mobilized as energetic a grassroots backlash against his plans today as they did in 1993 and 2009, respectively, and Biden’s approval rating has remained remarkably stable through late spring, while Clinton’s and Obama’s support (as well as Donald Trump’s) had already started slipping by then.

But many observers nonetheless see Biden facing a similar risk of a long, draining summer as crunch time in Congress approaches on his sweeping infrastructure and human capital plans and a long list of liberal priorities that have passed the House (headlined by national voting rights legislation) stack up in the Senate with little chance of approval unless Democrats can somehow reach agreement on retrenching or eliminating the filibuster.

Almost all recent presidents have seen their approval ratings sink from their inauguration through the end of their first summer in office, notes Brian Newman, a Pepperdine University political scientist who studies presidential performance.