The trial of a Louisiana congressman charged with bribery will be delayed so an appeals court can hear arguments on whether his status as a congressman protects him from prosecution.

The trial of Rep. William Jefferson, a Democrat, had been scheduled to start next Monday. His defense attorneys filed an appeal Wednesday in U.S. District Court in Alexandria.

The appeal had been expected since earlier this month, when U.S. District Judge T.S. Ellis III rejected an argument that the indictment should be tossed out because it unconstitutionally infringed on his privileges as a congressman.

Jefferson's attorneys argued that grand jury testimony given by his staffers violated the Constitution's speech or debate clause, which states that congressmen "shall not be questioned in any other Place" for speech or debate associated with their legislative work.

Ellis ruled that Jefferson's attorneys were trying to apply the principle too broadly.

Normally, defendants are only permitted to appeal a judge's ruling after trial. But a U.S. Supreme Court ruling states that questions involving the speech or debate clause can be filed on a pretrial basis.

Prosecutors can seek to have the appeal heard on an expedited schedule, but even then the delay is expected to last at least several months. The appeal will be heard by the 4th U.S. Circuit Court of Appeals in Richmond.

The indictment alleges Jefferson received more than $500,000 in bribes and demanded millions more between 2000 and 2005, including $90,000 he received from an FBI informant that was later found in the freezer of his Washington home.

Prosecutors allege he used his influence as chairman of the congressional Africa Investment and Trade Caucus to broker deals in Nigeria, Ghana, Cameroon and other African nations on behalf of those who paid bribes to him.