Suddenly, he can no longer be ignored.
The Illinois Democrat, appointed by disgraced former Gov. Rod Blagojevich, says he'll only vote for a bill to provide health care to millions more Americans as long as it allows the government to sell insurance in competition with private insurers.
And he says he won't compromise.
"I would not support a bill that does not have a public option," Burris, 72, said in a recent interview with The Associated Press. "That position will not change."
Those words caught the attention of the very Democratic leaders who tried to keep Burris out of the Senate, suggested he resign and have shunned him in unprecedented fashion. Burris is not the only Democrat to insist on creation of a government-run health plan. But he is the one who has the least to lose by defying President Barack Obama and the Democrats who once turned him out in the cold rain.
It was early January and Blagojevich had appointed Burris, a former Illinois attorney general, to Obama's former Senate seat - defying Democrats in Washington who had wanted someone without a tainted patron and with a better chance of winning election in 2010.
What happened next was a procession of ugly images, from Burris' rain-swept news conference after Democrats turned him away from a swearing-in to Illinois Rep. Bobby Rush daring Democrats to block an accomplished lawyer who would be the chamber's only black.
Bitterly, the Democrats seated Burris. But when it came out that Burris had admitted what he had denied under oath - that he'd unsuccessfully tried to raise money for Blagojevich - Majority Whip Richard Durbin, D-Ill., suggested that Burris resign. He refused.
A Senate ethics committee probe is pending into Burris' statements. Democratic leaders, meanwhile, refused to support any effort by Burris to run for a full term, and he will leave the Senate in 2011.
Meanwhile, his relationship with the rest of his caucus has settled into one of mutual, if chilly, benefit.
It works this way: Burris stays mum about any bitterness he may feel about his reception, and he gets Obama's Senate seat for two years. Democrats seat him, don't speak of him, and get his loyal vote at a time when all 58 Democrats and two independents must vote together to prevent Republican filibusters.
They've never needed 60 votes like they do on the yet-to-be-finalized health care bill. A disciplined grin shows that Burris knows it. No, he says, he will not vote for any version of a government-run plan circulating in the Senate, other than the full-blown one from the Senate Health, Education, Labor and Pensions Committee.
He won't vote, for example, for Republican Sen. Olympia Snowe's idea to use the threat of a public option to force insurers to lower premiums by certain deadlines. He hasn't seen the details of another idea, proposed by Sen. Tom Carper, D-Del., that would allow each state to decide whether to offer public coverage to compete with private insurers. The health committee's proposal, he says, must be in the final bill to earn his vote.
"Yeah, that's the one," Burris said.
By definition, all 100 senators are relevant because any one can block Senate business unless there are 60 votes to override the objection. But Burris' stated position on the public option means that Democrats can no longer take his vote for granted.
And yet, Democratic leaders aren't talking about Burris.
Instead, they're talking confidently about having the votes for the biggest policy overhaul in a generation, a signature issue for Obama and the Democratic Party.
Finance Committee Chairman Max Baucus, D-Mont., said Burris' demand alone makes him no different than other senators seeking this or that in the bill.
"I will do what I can to address the thises and thats," Baucus said. "But my strong feeling is in the end, the need for health care reform is to get 60 votes (and) is going to trump the concerns that some might have."
For his part, Burris says he's just representing the wishes of his state. And he's relentlessly loyal to the arrangement. His only acknowledgment of being treated differently than others is a reference to the "distractions" that marked his first weeks in office.
Ask him whether he feels badly treated by the leaders, and he'll answer with a question:
"By whose standard?"
Go a couple more rounds, and he'll elaborate, generally.
"I feel that I've had great opportunities here," Burris said. "I feel like anytime I had a question that needed answered, anytime I needed something, there was certainly assistance there."
Does he feel respected and listened-to? Burris pauses and looks puzzled.
"Yes. I'm a senator from Illinois representing 13 million people. I'm one of 100, and I speak on the floor, I preside over the Senate, I co-sponsor legislation," he says. "I'm very busy, I'm very challenged, and I have one problem."
"I enjoy what I'm doing."