The White House warned Thursday that America could not afford to be without a defense secretary, after Republican moves delayed a Senate confirmation vote on its nominee for the post, Chuck Hagel.

The Senate Armed Services Committee had been expected to vote on Hagel's nomination this week to prepare for a debate in the full chamber, but Republicans are demanding more information on Hagel's past paid speeches.

"We continue to expect the Senate to act quickly to confirm Senator Hagel," said White House spokesman Jay Carney.

"This is a uniquely qualified nominee for the post of secretary of defense. The position needs to be filled."

The Armed Services committee delayed Thursday's expected vote on the nomination after Republicans demanded more details of the speeches Hagel gave and was paid for after leaving the Senate in 2009.

Hagel's team and the White House however says the former senator has given voluminous details to the committee, including many remarks for which no text or transcript exists.

Hagel has angered several Republicans with some of his positions on Iran, Israel and US war policy.

In a Senate confirmation hearing last week he was grilled for hours on past positions on the Iraq war and sanctions regarding Tehran's nuclear program.

Republicans say they have yet to receive key information about payments that Hagel accepted for some of his speeches.

Jim Inhofe, the top Republican on the Armed Services Committee, said a lawmaker could seek to delay a vote in the full Senate by putting a hold on the nomination, should it manage to pass out of committee.