WASHINGTON —  The Republican leading a Senate inquiry of the government's botched response to Hurricane Katrina denied a Democratic request Wednesday to subpoena the White House for information.

Even though she has criticized the Bush administration for stonewalling, Sen. Susan Collins said the administration generally has provided enough information for the investigation to draw conclusions about federal failures before and after the Aug. 29 storm.

Collins, who heads the Senate Homeland Security and Governmental Affairs Committee, also said a subpoena could hinder President Bush's ability to receive candid advice from aides. Such communication usually is covered by executive privilege.

In a letter Wednesday, Collins, R-Maine, reminded the committee's top Democrat, Sen. Joseph Lieberman of Connecticut, that she issued five subpoenas to the Justice Department after its employees resisted being interviewed by Senate investigators.

"As a result of our efforts, we have a clear window into the functioning and role of the White House in the days before and after Hurricane Katrina made landfall," Collins said.

She added: "In my judgment, such subpoenas are neither warranted nor appropriate."

In January, Collins and Lieberman criticized the White House for withholding documents and testimony from presidential advisers and for barring employees at federal agencies from complying.

Asking for the subpoena, Lieberman said that "nothing less than the future preparedness of our nation to respond to a terrorist attack or another catastrophic natural disaster is at stake."

House Republicans rejected a similar subpoena request by Democrats this year.

The Senate committee is wrapping up its investigation into the failed planning for and response to the storm that devastated the Gulf Coast.