You do sense that the momentum is shifting in the Senate on the issue of seating the Junior Senator from Illinois, as Roland Burris likes to identify himself:

No one in the Democratic leadership suggested Monday that Burris would actually be seated when he arrives at the Capitol on Tuesday — or at any point thereafter — but the rhetoric was clearly softening as a potential showdown at the Capitol loomed, and Democrats were eager to get past the distraction.

Burris, arriving on a Southwest Airlines flight to Baltimore/Washington International Thurgood Marshall Airport, acted as if his future wasn’t in doubt. He declared: “I am the United States senator from the state of Illinois.” And asked whether he’d anticipated the “mess” his appointment would cause, Burris said, “Mess? What mess?”

Burris is expected to arrive at the Capitol on Tuesday just before the swearing-in ceremony for new members. He said his message for Reid is simple: “I’m here to take my seat.”

Considering the pressure from Republicans and African-Americans in the House plus the flimsy legal grounds for excluding Burris ( “There must be fraud in there somewhere“), you wonder how Reid is going to wriggle out of his defiant position.

He could always offer to seat Burris, with the understanding that Burris won’t run again in 2010. But why should Burris agree to that? Reid alternatively could agree to seat Burris pending a special election, but the Illinois Democrats are dead set against that and, again, Burris would have no real reason to agree to such a deal.

Whatever “deal” Reid has in mind looks increasingly like a capitulation. And that, after all, is the “right” result. Burris has done nothing wrong from what we know. It’s Blago, the Illinois Democrats and the Senate Democrats who seem to be playing fast and loose with the law. And Burris knows it.