Democratic senators are tied to the ticket’s reputation.

Democrats faced a challenging path to holding their Senate majority even before President Joe Biden’s disastrous debate performance and the assassination attempt against former President Donald Trump – and they still do. But this year’s Democratic candidates, many of them well-known incumbents, have so far been able to create some separation from the top of the ticket. The question going forward, regardless of what Biden does, is whether they can sustain it.

Nine of the top 10 seats on CNN’s latest ranking of the Senate seats most likely to flip are held by Democrats (or independents who caucus with them). And assuming Republicans flip West Virginia, where Sen. Joe Manchin is retiring, the GOP just needs to win the White House or pick up one more Senate seat to win the majority.

That’s a tough landscape for Democrats – especially when they’re defending seats in states that either twice voted comfortably for Trump (Montana and Ohio) or are presidential battlegrounds, and when Biden is so far defying intraparty warnings that his candidacy could cause a GOP “landslide.” Montana Sen. Jon Tester and Ohio Sen. Sherrod Brown – the two most vulnerable incumbents running for reelection – said this week that Biden should exit the race.

There’s been limited public polling of Senate races since the increasing Democratic consternation in the debate’s aftermath and virtually none since the attack on Trump in Pennsylvania last week. There has, however, been some slippage in Biden’s numbers, and Democrats are bracing for Trump, who officially claimed the GOP nomination in Milwaukee this week, to receive a post-convention polling bump.

All of that raises the stakes for Senate Democrats to keep doing what they’re doing: touting their legislative accomplishments without invoking the Biden administration and using their fundraising edge to try to define their GOP challengers – often by mining their business backgrounds and out-of-state ties. Democrats have also been hitting back on attacks over the southern border by highlighting their support of bipartisan immigration legislation that Republicans killed in Congress this year.

But the risk for Democrats is that as their Republican challengers become better known, GOP campaign spending increases and more voters tune in, any separation from the top of the ticket will erode. Ticket-splitting isn’t as common as it once was, as CNN political analyst Ronald Brownstein wrote recently.