Sen. Ben Ray Luján (D-N.M.) suffered a stroke last Thursday and is recovering in an Albuquerque hospital, his office said Tuesday. After feeling dizzy and fatigued, Luján, 49, checked himself into the hospital and "subsequently underwent decompressive surgery to ease swelling," his chief of staff said in a statement. "He is currently being cared for at UNM Hospital, resting comfortably, and expected to make a full recovery."  This was evidently the first many of his colleagues heard about Luján's medical condition.  "Jesus. He had a stroke? First I've heard of it," Sen. Jon Tester (D-Mont.) told Politico. "Oh, my God. I'll find out. I did not know that, wow. It makes me worried about him, he's too young for that stuff." Luján's fellow New Mexican, Sen. Martin Heinrich (D), also learned about the stroke Tuesday, and Senate Majority Whip Dick Durbin (D-Ill.) didn't know until reporters told him.  Luján's stroke was a reminder for Democrats that their control of the evenly divided Senate is fragile and hostage to the whims of fate. His absence won't affect President Biden's Supreme Court confirmation project immediately, but Biden would need his vote if no Republicans voted to confirm his nominee. Some Democrats suggested Senate leaders may need to adjust their agenda to focus on legislation with bipartisan support. Democrats have a little bit of breathing room, because two Republican senators — Mitt Romney (Utah) and John Hoeven (N.D.) — are in quarantine after COVID-19 diagnoses.  Two other sitting senators — Tim Johnson (D-S.D.) and Mark Kirk (R-Ill.) — "suffered strokes in recent history, leading in both cases to extended absences," the Post reports. "Their strokes were of a different types than Lujan's," but if Johnson had been forced to step down, he would have been replaced by a Republican, shifting the Senate from a 51-49 Democratic majority to a 50-50 split with the GOP in control. If Luján needed to vacate his seat, the Post adds, "New Mexico Gov. Michelle Lujan Grisham (D) — who happens to be a distant cousin of Luján — would appoint a replacement." "My hope is that Ben Ray will put himself first for the next few weeks so he gets an absolutely full recovery, because I can't do this job without his help," Heinrich told reporters.