Washington ? Top administration officials pressed Congress on Thursday to quickly send President Bush the $74.7 billion he wants to begin paying for the war with Iraq, and didn’t rule out needing even more money before the year ends.

Bush proposed the measure on Tuesday and has asked lawmakers to complete the legislation by April 11, which would be lightning fast action for Congress.

House and Senate leaders plan to whip initial versions through their chambers by the end of next week, though disputes are raging over flexibility Bush wants in spending the money and add-ons lawmakers want for local law enforcement and struggling airlines.

Many lawmakers have expressed doubt that Bush’s figure would fully cover the U.S. buildup, combat against Iraq, and the expensive postwar role America will probably play in peacekeeping, humanitarian aid and reconstruction.

Citing uncertainty over the duration of the fighting and other factors, Defense Secretary Donald Rumsfeld repeatedly stopped short Thursday of assuring the legislators that the requested money would be sufficient. He said the request — $62.6 billion of which goes to the Pentagon — is designed to last through Sept. 30, when the government’s budget year ends.

“Is it going to prove out over the coming months? I don’t know,” Rumsfeld said of the figure to the Senate Appropriations Committee. “Do we believe it is the best possible estimate at the current time? Yes.”

Later, discussing with senators whether the money would last through September, Deputy Defense Secretary Paul Wolfowitz said, “Even that you can’t say with confidence.”