Nancy Erickson, the Senate secretary, initially rejected Burris' appointment Monday because his certificate of appointment was missing the signature of Illinois Secretary of State Jesse White.

CNN: Feinstein says Burris should get Senate seat

Democrats expect Burris to show up on Capitol Hill on Tuesday with a certificate of appointment signed by Blagojevich but missing the signature of Illinois Secretary of State Jesse White, according to the Democratic source and a Democratic Senate leadership aide.

CNN: Burris to meet with Dem leaders, source says

On Monday Senate officials ruled that Mr Burris's appointment was not legal because his certificate has not been signed byIllinois's secretary of state, as well as the governor, as the rules require.

ECONOMIST: American politics