Updated: 7:38 p.m.

Sen. Mark Kirk (R-Ill.) might need months to recover from a major stroke that he suffered over the weekend, but his absence is not likely to have any major political repercussions for his party or the Senate.

The freshman Senator underwent “successful” surgery Monday and is recovering in a Chicago hospital, according to a spokesman.

Kirk, 52, had the stroke Saturday and checked himself into a suburban Chicago hospital, where doctors discovered a tear in one of the two main arteries that delivers oxygenated blood to the brain. He was then transferred to Northwestern Memorial Hospital, where doctors operated on him to “relieve swelling around his brain stemming from the stroke.”

“The surgery was successful. Due to his young age, good health and the nature of the stroke, doctors are very confident in the Senator’s recovery over the weeks ahead,” the Kirk spokesman said.

Sen. Tim Johnson (D-S.D.) missed almost 10 months of work after suffering bleeding in the brain after a congenital cardiovascular mass caused stroke-like conditions in December 2006. In 2010, Johnson was elevated to Senate Banking chairman, but he still has difficultly walking and talking.

Johnson missed the beginning of the 110th Congress, which at the time was almost completely evenly divided between the parties. Senate Majority Leader Harry Reid (D-Nev.), who had just assumed the reins of the chamber, struggled to move legislation because his bare 51-vote majority had been reduced to 50 with Johnson’s absence. Given the current composition of the Senate, the 47-Member GOP Conference does not need Kirk to muster the 41 votes required to mount a filibuster. And Democrats, who have not been able to move bills without a large swath of GOP votes, likely will not have to change their calculus either.

But the Illinois Republican’s presence will be missed, especially on the issue of Iran — where the first-term Senator has emerged as a leader — as he convalesces in Illinois.

Kirk is also one of the more moderate Members of the GOP caucus and has been a frequent partner with other Republicans and Democrats on initiatives such as infrastructure.

“He’s is sort of a bipartisan guy, always looking to build a consensus on both sides, and someone who is likely to move forward if Democrats offer some sort of reasonable proposal,” one Senate source said. “In the sense that Democrats would be hopeful that they could get to 60 on any tight vote, then they might have more difficulty now.” The source added that, “In the long term, he’d have a year to recover and prepare for a position for a subcommittee gavel” if Republicans take back control of the chamber in this year’s elections.

Still, Kirk’s condition Monday appeared serious. Dr. Richard Fessler, Kirk’s neurosurgeon at Northwestern Memorial, said doctors removed a 4-by-8-inch piece of the Senator’s skull to relieve the swelling caused by the damaged tissue, a maneuver common in brain trauma cases.

The stroke did not affect the Senator’s left brain, meaning his cognitive and language skills likely will be intact as he recovers, Fessler said during a press conference at the Chicago-based hospital. Fessler indicated Kirk’s prospects for “a full mental recovery are good,” but that the Senator’s “prospects for a full physical recovery, particularly on his left side, are not great.”

The doctor also noted it was “way too soon to try and predict” how long Kirk will need to recuperate, but that his convalescence could take weeks or months.

Kirk’s doctor said that when taken off sedation, Kirk has been responsive to commands and aware of those around him — both good indicators of potential and complete cognitive recovery.

In the meantime, Senate Majority Whip Dick Durbin (D-Ill.) has offered to assist the junior Senator’s office in any way necessary.

“I was stunned to learn that Mark suffered a stroke. He is young and in good physical condition and I have no doubt he will make a speedy recovery,” Durbin said in a statement. “I have reached out to his staff and offered to do anything I can to help with his Senate duties.”