Late last week, a group of 16 Republican senators, led by Georgia Sen. David Perdue, sent a letter to Senate Majority Leader Mitch McConnell asking the leader to make them work longer hours. Citing the slow pace of confirming presidential nominees and an interest in getting next year’s appropriations bills done on time, the signers said they would be willing to work “nights and weekends and forgo the August recess” to complete their work.

McConnell hasn’t made a decision about canceling August recess, also known as the six-week “state work period,” just yet. But it’s an idea that President Trump endorsed over the weekend. “The Senate should get funding done before the August break, or NOT GO HOME,” he tweeted Saturday afternoon. “Wall and Border Security should be included. Also waiting for approval of almost 300 nominations, worst in history. Democrats are doing everything possible to obstruct, all they know how to do. STAY!”

Senate Democrats, as you may have noticed from their lack of signatures on the letter, or a letter of their own, are much cooler to the idea. Senate Minority Leader Chuck Schumer, when asked repeatedly whether it might be necessary to cancel the August recess during his Tuesday press conference, reiterated that they have “plenty of time to get our work done” by the time current appropriations expire at the end of September. Both he and McConnell noted that there appears to be real cooperation between the two sides on the process this time, which would smooth the ability to get each of the 12 appropriations bills done on time rather than through a loaded omnibus package—which President Trump has said he wouldn’t sign again.

Why would there be more enthusiasm among Senate Republicans than their Democratic counterparts for staying in session during a planned six-week recess? Some of it is scoring presidential suck-up points, the coin of the realm among Republican legislators. But there’s another big issue at play: the Senate map.

Senate Democrats (and the independents who caucus as Democrats) will be defending 26 of the 35 seats up for election this cycle, and the August recess is a critical time for campaigning. McConnell, as a source told CNN, is “seriously considering” canceling at least some of the recess. The source cited the favorable politics of the move. (Though there are two Republican senators, Nevada’s Dean Heller and Texas’ Ted Cruz, who face serious election challenges this year, they don’t seem too nervous about missing their own time, as they’ve both signed the letter.)

The threat of canceling an August recess, even in a non-election year, can move mountains. Though any individual senator can slow the Senate—an institution built on consent—to a crawl if he or she so desires, the Senate can move quite quickly when the consent is there. That’s what happened after McConnell announced he would cancel the first two weeks of August recess last year. The Senate only ended up staying one additional week, and confirmed a host of additional nominees en bloc at the snap of the leader’s fingers.

“Many of us encouraged cancelling August recess last year to meet our legislative goals,” the Republican senators wrote in their letter to McConnell last week. “As a result, the Senate confirmed 77 nominations with no floor debate, a significant concession from the minority party. Our diligence was rewarded with reason, and it can happen again.”

It can. Especially in this cycle.