Washington (CNN) - Despite his sharp criticism of cabinet nominee Chuck Hagel, Sen. John McCain said Monday he would oppose any effort by his colleagues to block an up-or-down vote on President Obama's pick to run the Department of Defense.
"I do not support a filibuster," McCain said. "I don't think it's appropriate and I would oppose such a move."
The Arizona senator told reporters Tuesday he had not decided whether to support Hagel's nomination, but said he would try to persuade his colleagues not to delay a vote. To overcome a filibuster, 60 senators must vote to end debate on the nominee and force a vote - a higher threshold than needed to confirm him.
Traditionally, senators are reluctant to filibuster a presidential Cabinet pick, and view the nominations as the president's prerogative. In the country's history, a Cabinet nominee has never faced a formal filibuster that required 60 votes to break, according to Betty Koed of the Senate Historian's Office.
Over the weekend, Senate Minority Leader Mitch McConnell told Kentucky TV station CN2 that "opposition to [Hagel] is intensifying," and said it was "not clear yet" whether Hagel would need the 60 votes necessary to overcome a filibuster.
As a long-time member of the Senate Armed Services Committee, McCain is considered an influential voice on military issues, and his decision on Hagel could sway his colleagues.
Old friends, Hagel and McCain clashed during last week's confirmation hearing, when McCain accused Hagel of dodging a question on Iraq war policy.
"To any casual observer I was obviously not happy with his failure to answer a really simple question," McCain said, adding he was waiting for a response from Hagel on additional questions before making his decision on whether to support him.
–CNN Senior Producer Ted Barrett contributed to this report.