Lawmaker's stroke highlights constraints of evenly divided Senate

The absence of Sen. Ben Ray Lujan from the Senate is casting new light on the constraints of the evenly divided chamber, with the Democrat's absence already sidelining some committee activity and throwing the timeline for other Democratic priorities into question.

Lujan, a New Mexico Democrat, suffered a stroke Thursday and underwent surgery to relieve pressure following the incident. It is unclear how long the 49-year-old will be gone as he recuperates, though his office reports he is expected to make a full recovery and return to work in four to six weeks, barring something unforeseen, according to a senior aide to the senator.

Democrats currently hold the narrowest of possible majorities in the Senate, and an absence of an unknown length from even one Democratic senator threatens to sideline priorities that Democrats may have needed the strength of their full caucus to push through.

In floor remarks Wednesday, Senate Majority Leader Chuck Schumer wished Lujan a swift recovery but did not address the way his absence could impact the Senate schedule.

"All of us are hopeful and optimistic that he will be back to his old self before long," Schumer said. "In the meantime, the U.S. Senate will continue to move forward on carrying out its business on behalf of the American people."

Already, the Senate Commerce Committee on which Lujan serves has had to delay votes on multiple nominees who are not supported by Republicans. An aide for the committee told ABC News that committee votes on three different nominees were rescheduled from Wednesday morning "to take into consideration the need for all Democratic votes in order to move certain nominees forward."

Nominees are a central concern, with many federal and judicial nominees scheduled for votes on the Senate floor in the coming days. It's unclear how Lujan's absence might affect Democrats' ability to confirm those who are not supported by Republicans.

The matter puts increased focus on Senate Democrats' effort to swiftly fill a vacancy on the Supreme Court left by retiring Justice Stephen Breyer. But Senate Judiciary Chairman Dick Durbin told reporters Wednesday that Democrats "don't anticipate any difficulties" moving forward with the nomination.

Lujan does not serve on the Judiciary Committee, which will hold hearings and ultimately vote on Biden's yet-to-be-named nominee before they are considered by the full Senate. Biden said he may not name the nominee until the end of the month, and from there, Durbin is aiming for a 40-day confirmation process, which buys Democrats considerable time.

"We hope Sen. Lujan is back soon, we are waiting for the nominee from the President and the clock will start running when we receive it," Durbin said.

It's also not yet clear whether any Republicans will support the nominee. The support of even one Republican would make it possible for the nominee to be confirmed in Lujan's absence, and several Republicans, including Sen. Lindsey Graham, R-S.C., and Sen. Susan Collins, R-Maine, have signaled some willingness to work with Democrats on the matter.

Democrats had also hoped February could yield renewed conversations on Biden's social spending agenda, which would require the unanimous support of all 50 Senate Democrats to pass.

But that agenda is stalled with or without Lujan. Sen. Joe Manchin, D-W.Va., whose opposition to the Build Back Better plan quashed its chances in December, declared that Build Back Better, at least as it's currently understood, is "dead" on Tuesday. Manchin said he isn't currently engaged in talks on the matter and, until his demands are satiated, Lujan's absence is a moot point.

Still, other key priorities Democrats are hoping to move through the chamber this month are not yet being sidelined by Lujan's absence because they will require at least 60 votes on the Senate floor. In fact, Lujan's absence only stands to highlight the work of multiple bipartisan working groups that have emerged in recent weeks to chart a path forward on items like voting rights, government funding and Russian sanctions.

A bipartisan group led by Collins is looking at possible reforms to the Electoral Count Act which governs how Congress handles the tabulation of electoral votes. This new effort emerged from the ashes of a failed attempt at voting reform effort led by Democrats last month, which came after they were unable to modify the Senate filibuster rules.

A bipartisan group met on these renewed, narrower election reform efforts earlier this week and is holding another round of meetings with the Democratic chair and Republican ranking member of the Senate Rules Committee on the matter later Wednesday.

Bipartisan meetings between leaders in both the House and Senate are also ongoing to discuss a path forward on government funding. Lawmakers will need to cobble together a solution to extend government funding before Feb. 18 in order to avoid a government shutdown, and by all accounts, they expect a bipartisan outcome to avert one.

Republican buy-in will also be a necessity to authorize sanctions against Russia. The country's increased hostility toward Ukraine has prompted bipartisan work between Senate Foreign Relations Committee Chair Bob Menendez and Ranking Member Jim Risch that has brought other lawmakers from both sides of the aisle into the fold.

ABC News' Rachel Scott and Trish Turner contributed to this report.