Sen. Mary Landrieu (D-La.) threatened yesterday to hold President Bush’s executive-branch nominees hostage until the administration agrees to a series of demands that would increase funding for coastal Louisiana.

In a letter sent to Bush yesterday, the Louisiana Democrat threatened to place holds on the president’s nominees, raising the prospect that the Senate could be tied in knots as Bush tries to fill a variety of vacancies, including the top jobs at the Interior Department and the Office of Management and Budget.

“Because this is literally a life-or-death situation for the people of my state, I am compelled to notify you that I will exercise my power as a member of the Senate to stop further consideration of all executive appointments until significant progress is made on such a request and commitment,” Landrieu wrote.

She is looking for an additional $6 billion for levees, flood control and coastal restoration in Louisiana — and the president’s commitment to use “the full weight of the office of the president” to pursue that money, a plan for coastal restoration and a federal revenue-sharing arrangement for receipts from Outer Continental Shelf drilling.

The price tag matches the new figure the administration has said would be needed to bolster Louisiana’s levee system to the point that the area would be eligible for federal flood insurance. A $95 billion supplemental spending bill marked up by the Senate Appropriations Committee yesterday already contains about $2 billion for the Louisiana coast.

Senators have been able to block nominations — or legislation — indefinitely by using the informal “hold” procedure. Senate Republican leaders could circumvent holds on nominations by calling for cloture, but each nomination would require a separate cloture vote. That could add days to the timeline for each nomination.

But the likelihood of high Senate floor drama was not yet clear yesterday. “Historically, a blanket hold does not necessarily accomplish the goal [or goals] set out for it when deployed,” said Eric Ueland, chief of staff to Senate Majority Leader Bill Frist (R-Tenn.).

“Mr. President the piecemeal approach that has marked your administration’s response to providing adequate levee and flood protection for Louisiana has not worked,” Landrieu wrote. “It needs to be replaced by a comprehensive approach that is both more effective and cost-efficient.”

Louisiana lawmakers have run into strong resistance from conservative Republicans on recent requests for Gulf Coast funding. The conservatives argue that new money for the region should be offset by budget cuts.

With singular purpose, Landrieu has begged, bargained and beguiled in search of federal assistance for Louisiana since Hurricane Katrina devastated the Gulf Coast last summer. Yesterday, she promised to up the stakes for the administration.

“It’s the leverage I have,” Landrieu said.

She hinted that she has other arrows in her quiver but did not specify what other means she might have to put pressure on the president or the GOP-led Senate.

Landrieu did not rule out offering a floor amendment to the supplemental appropriations measure on the floor to accomplish her goal, but her aides said it would be difficult to get the money without backing from the White House.

Last month, Landrieu was the only Democrat to vote for the budget resolution, after she struck a deal with Frist and several senior Republicans that would provide $10 billion to Louisiana for similar purposes if a number of conditions are met.

But many lawmakers and aides have cast doubt on the prospects of final adoption of a conference report on the budget this year. The House is scheduled to vote on its version of the legislation this week.

“Money spent on levees and flood control today will save the federal government billions in the future by eliminating the need for costly post-storm recovery and rebuilding in areas that were not adequately protected,” Landrieu wrote. “The people of my state cannot wait any longer. We can no longer rely on promises. We need action, and we need action now.”

As for Landrieu’s threat, Ueland said Frist will not prematurely “cross any bridge.”