Even as negotiations on a Wall Street rescue package appeared to be progressing, Senate leaders and Sen. John McCain (R-Ariz.) continued to spar over whether the presidential candidate should have suspended his campaign to deal with turmoil in the financial markets.

Senate Majority Leader Harry Reid (D-Nev.) mocked McCain’s return to Washington as nothing more than a distraction from the delicate talks that were occurring without him, even as he insisted that the principles laid out by Democratic presidential nominee Sen. Barack Obama (Ill.) “must be in any package.”

“All he has done is stand in front of the cameras,” Reid said of McCain, noting that he first called for the GOP nominee to “take a stand” on the bill earlier this week. “We still don’t know where he stands on the issues.”

McCain’s campaign fired back in a statement: “At a moment of crisis that threatened the economic security of American families, Washington played the blame game rather than work together to find a solution that would avert a collapse of financial markets without squandering hundreds of billions of taxpayers’ money to bailout bankers and brokers who bet their fortunes on unsafe lending practices.”

McCain also said he would resume campaigning and attend tonight’s presidential debate.

Meanwhile, Senate Minority Leader Mitch McConnell (R-Ky.) and the Senate GOP’s chief negotiator on the bailout, Sen. Judd Gregg (N.H.), praised McCain’s and Obama’s decisions to return to Washington during the debate on the financial market crisis.

“Sen. McCain and Sen. Obama’s coming back to Washington significantly moved the process along,” Gregg said. “I think that was constructive.”