Senate Republican leader Mitch McConnell is back at work in the U.S. Capitol on Monday, almost six weeks after a fall at a Washington-area hotel and extended treatment for a concussion.

The longtime Kentucky senator, 81, has been recovering at home since he was released from a rehabilitation facility March 25. He fell after attending an event earlier that month, injuring his head and fracturing a rib.

McConnell arrived at the Capitol early Monday and is expected to work a full schedule in the Senate this week.

In brief remarks on the Senate floor as the chamber came back into session after a two-week recess, McConnell criticized President Joe Biden for not doing enough to negotiate on the nation's debt ceiling and thanked his colleagues for their well-wishes.

“I'm very happy to be back,” McConnell said. “There's important business for Congress to tackle.”

And he joked, “Suffice it to say, this wasn't the first time that being hard-headed has served me very well.”

McConnell returns to the Senate ahead of a busy stretch in which Congress will have to find a way to raise the debt ceiling and negotiate additional aid for the Ukraine war, among other policy matters. And he comes back as several other senators have been out for medical reasons, raising questions about how much the Senate will be able to achieve in the coming months with a 51-49 split between the parties.

Already, the GOP leader's absence, along with those of Democratic Sens. Dianne Feinstein and John Fetterman, among others, have added to the Senate's lethargic pace in the first few months of the year. Unlike the last two years, in which Senate Majority Leader Chuck Schumer was able to push through key elements of President Joe Biden's agenda with the help of a Democratic-led House, the Senate has been significantly slowed with Republicans now in charge in the House. And absences have made even simple votes like nominations more difficult.

One immediate question for McConnell upon his return is whether to help Democrats temporarily replace Feinstein on the Senate Judiciary Committee as she continues to recover in California from a case of the shingles. Democrats have become increasingly frustrated as the Democrat's more than six-week absence on the panel has stalled confirmation of some of Biden’s nominees, and Feinstein has asked for a short-term substitute on the committee.

Democrats can’t do that, though, without help from Republicans, since approval of the process would take 60 votes on the Senate floor. Republicans have so far been quiet about whether they will object.

It is unclear when Feinstein, 89, will return to Washington. Her office has so far declined to say.

Also returning to the Senate on Monday is Fetterman, who was hospitalized for clinical depression in February. He was treated for six weeks at Walter Reed National Military Medical Center, and his doctors say his depression is now “in remission.”

Fetterman’s announcement that he was checking himself into the hospital earlier this year came after he suffered a stroke last year and has struggled with auditory processing disorder, which can render someone unable to speak fluidly and quickly process spoken conversation into meaning. The Pennsylvania Democrat, 53, now uses devices in conversations, meetings and congressional hearings that transcribe spoken words in real time.

In a statement when he was released from Walter Reed late last month, Fetterman said the care he received there “changed my life."

“I’m excited to be the father and husband I want to be, and the senator Pennsylvania deserves,” said Fetterman, who won praise for his decision to seek treatment.

When McConnell visited his Capitol office on Friday, video captured by NBC News showed him walking into the building without assistance as aides kept close by.

This was the second major injury for McConnell in recent years. Four years ago he tripped and fell at his home in Kentucky, causing a shoulder fracture that required surgery. The Senate had just started a summer recess, and he worked from home for some weeks as he recovered.

McConnell had polio in his early childhood and he has long acknowledged some difficulty as an adult in climbing stairs.