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Illinois Gov. Rod Blagojevich's surprising and defiant decision to appoint a replacement for Barack Obama in the Senate seat could lead to a racially-charged showdown in Washington.

On one side, Obama, who will become the country's first black president, has said former state Attorney General Roland Burris, the first black to win a statewide office in Illinois, shouldn't be seated because of the corruption case against Blagojevich.

On the other side, members of the Congressional Black Caucus are warning their fellow counterparts in the Senate not to block the appointment of someone who would be the chamber's only black member.

U.S. Rep. Bobby Rush forcefully backed Blajogevich's decision on the basis of race this week, warning the public not to "lynch" Blajojevich's Senate pick.

"This is a matter of national importance," Rush said at the news conference announcing the selection of Burris for the job. "There are no African-Americans in the Senate, and I don't think that anyone, any U.S. senator who's sitting in the Senate right now wants to go on record to deny one African-American for being seated in the U.S. Senate."

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    Other caucus members, without referring to race, still stood in favor of seating Burris.

    "Burris has been appointed by the governor and I think it would probably work to everybody's benefit," Maryland Rep. Elijah Cummings told FOX News. "This is a guy who's 73 years old. Let him go ahead and serve the two years. He's probably not going to run again and then let somebody else come and run."

    Obama overcame predictions that the issue of race would derail his 2008 presidential campaign. But no one could have predicted how race has become a factor in the battle over how to appoint a successor to Obama's Senate seat.

    This brewing battle could trump any debate about race on the 2008 campaign trail. And Washington observers are wondering if it has the potential to distract the first incoming president and the Democratic-controlled Congress before it even gets down to legislative business.

    In a statement released this week, Obama called for Blagojevich to resign, allowing for a lawful and appropriate process of succession to occur.

    "Roland Burris is a good man and a fine public servant, but the Senate Democrats made it clear weeks ago that they cannot accept an appointment made by a governor who is accused of selling this very Senate seat," Obama said. "I agree with their decision, and it is extremely disappointing that Gov. Blagojevich has chosen to ignore it."

    Obama said Gov. Blagojevich is entitled to his day in court but "the people of Illinois are entitled to a functioning government and major decisions free of taint and controversy."

    Burris has made it clear that he is coming to Washington on Tuesday. But Democratic leader Harry Reid, D-Nev., has made it equally clear that the Senate will use its Constitutional powers to block him.

    Burris faces another obstacle in his own state: Illinois Secretary of State Jesse White is refusing to sign off on the appointment. Burris filed a motion with the state Supreme Court seeking to force White to sign it.

    White, who is black, told FOX News that he can't sign off on the appointment because Blagojevich is under a "cloud of controversy" and added that race played no part in his decision.

    "The person could have been pink, blue, green or yellow. My mission and my attitude and my commitment is the same," he said.

    But race is playing an increasing role in this ongoing saga. At a news conference Friday, about a dozen black activists said -- despite the legal cloud over Blagojevich -- the governor has the legal right to appoint Burris, adding that Burris is highly qualified.

    William Walls of the Committee for a Better Chicago warns that if White doesn't certify the appointment and Sen. Dick Durbin doesn't support Burris, activists will work to defeat them in upcoming elections.

    Burris also has received support from the Chicago Sun Times in an editorial Friday.

    "Secretary of State Jesse White, despite what Blagojevich's foes might wish, has no legal or constitutional grounds to refuse to sign off on the appointment," the editorial read. "If a secretary of state could kill gubernatorial appointments merely because a governor is an unpopular goof, there would be no end to it."

    The newspaper, however, added it would have preferred a special election or Blagojevich to step aside and allow the lieutenant governor to make the Senate appointment.

    Without his credentials from White, Burris may not be able to get inside the Senate chamber. Attendants who man the doors of the Senate chamber will not permit Burris to enter the floor, a Senate Democratic leadership aide told FOX News.

    Jim Manley, a senior spokesman for Reid, told FOX News a resolution to refer Burris' credentials to the Rules Committee would be offered if the certificate problem is resolved in Burris' favor.

    But Reid's original intent of blocking Burris would still stand, Manley said.

    "He will not become a U.S. Senator," Manley said, stressing that this is about Blagojevich, not Burris.

    Any delay would buy time for the Illinois Legislature to complete its impeachment inquiry of Blagojevich, which would render his appointment null and void should Blagojevich be removed from office before Burris is seated.

    FOX News' Molly Henneberg, Trish Turner, Chad Pergram and The Associated Press contributed to this report.