Slate.com: The Powell Case does not apply...

From Slate.com's article: "How the Senate Can Stop Blagojevich":

In short, easily.

Following English parliamentary tradition and early Colonial and state practice, the framers made the Senate its own gatekeeper and guardian. Each house of Congress is "the Judge of the Elections, Returns, and Qualifications of its own members," according to Article 1, Section 5 of the Constitution. At the founding, Senators were elected by state legislatures. If the Senate believed that legislators in a given state had been bribed into voting for a particular candidate, the Senate could refuse to seat him.

And in case you were wondering about the Adam Clayton Powell case a lot of Legal Pundits have been bleating on about:

In the 1969 case of Powell v. McCormack, the Supreme Court properly held that the Constitution imposes limits on the power of the Senate and the House to exclude members. Some legal commentators say this decision trumps the Senate's power to exclude Burris. But the letter and spirit of Powell actually cut against him. The case involved an elected congressman, Adam Clayton Powell, whom the voters had clearly chosen in a fair election and whom the House nevertheless excluded—wrongly, the court held. The key fact is that there was no doubt whatsoever that Powell was the people's choice, and in issuing its ruling, the Warren Court repeatedly stressed this. The justices insisted that their ruling was aimed at protecting the people's right to vote. None of that spirit applies here. And that's why the case doesn't stand in the Senate's way now.

Powell also said that each house could "judge" the qualifications laid out in the Constitution (such as age) but could not make up new qualifications. Thus, if the Senate were to plausibly decide in good faith that a candidate failed to meet the Constitution's age requirement, Powell nowhere suggests that this senatorial determination should be set aside by ordinary federal courts. For similar reasons, federal courts should not interfere when the Senate plausibly and in good faith decides an election or return to be improper or corrupt. The critical point here is that the Constitution itself sets up the Senate as the highest court of Senate elections. When the Senate speaks as this court, its adjudications are legal judgments that no other court may properly reopen. If the Senate convicts a federal judge in an impeachment court, no other federal court may properly interfere. So, too, for Senate elections and returns.