In the letter, dated Friday, attorney Timothy Wright called on the Senate leaders to grant the people of Illinois the representation the U.S. Constitution affords them.

The letter was addressed to Dick Durbin of Illinois, Charles Schumer of New York and Dianne Feinstein of California and to Reid, who has said that anyone picked by Blagojevich will be turned away.

Wright, who said he hadn't received a response to the letter as of Saturday, told The AP that he planned to go to federal court if the Senate refuses to seat Burris.

Burris has already asked the Illinois Supreme Court to force Illinois Secretary of State Jesse White to certify the appointment, hoping it will help his argument to be seated.

Telephone and e-mail messages left by The AP for Wright on Saturday were not immediately returned.

Reid urged Blagojevich to appoint either Illinois Veterans Affairs chief Tammy Duckworth or Illinois Attorney General Lisa Madigan, the Chicago Sun-Times reported Saturday, citing anonymous sources.

Reid reportedly opposed the appointments of Democratic Reps. Jesse Jackson Jr. and Danny Davis because the Democratic leader feared they would lose the seat to a Republican in the 2010 general election. Reid also allegedly opposed Emil Jones, the powerful black leader of the Illinois Senate, on the same grounds.

"What is clear to me is that every candidate that was African-American was denied and every other candidate was acceptable," said Wright, adding, "I'm not going to read too much into that."

Wright also echoed Blagojevich's claim of a conflict of interest, saying that Reid's call to the governor showed he had a political stake in who took Obama's seat.