WASHINGTON — An iffy health care vote. An unresolved budget resolution. A heavy debt ceiling lift. And, of course, there is that tax overhaul plan.

Congress has a lot to do, and it doesn’t have much time. So much for a lazy July in Washington.

When members of Congress return next week from their Fourth of July break, they will be greeted by a mammoth legislative logjam. Republicans are increasingly skeptical that they can get everything done. There are even calls from some to forgo their sacred August recess — a respite from the capital in its swampiest month.

“Our current Senate calendar shows only 33 potential working days remaining before the end of the fiscal year,” a group of 10 Republican senators wrote on Friday in a letter to Senator Mitch McConnell of Kentucky, the majority leader, highlighting the deadline at the end of September. “This does not appear to give us enough time to adequately address the issues that demand immediate attention.”

The Republican Party is under intense pressure to achieve something of consequence in that limited time in order to legitimately claim that the first year of the Trump administration has been a success. So far, the ambitious agenda has stagnated without a signature achievement. President Trump’s unpredictability has only made matters more complicated.