WASHINGTON, April 23: The US House of Representatives mulled its own possible demise on Thursday as it approved doomsday legislation to speed its replacement in case of a widespread loss of lawmakers.

Passed on a 306-97 vote, the measure would require special elections within 45 days if more than 100 of the 435 House members were ever wiped out. Such mass casualties would hamper the chamber's ability to conduct business - such as helping provide funding and advice for any retaliation against a hit on Capitol Hill.

"The tragic events of Sept 11, 2001, made clear that - much as we might wish otherwise - that at some point in the future it may be necessary to replace a large number of members of this body killed in some type of terrorist attack," said Rep Doc Hastings, a Washington state Republican.

One of four airliners hijacked on Sept 11, 2001, is suspected to possibly have had the Capitol in its cross-hairs until passengers tangled with their captors, sending the aircraft into a Pennsylvania field.

"Those passengers gave their lives to give us a second chance," said Rep Brian Baird, a Washington state Democrat. While the bill won broad support, Mr Baird and several other members, mostly Democrats, complained it was inadequate and would leave the House for too long with too many empty seats.

Many favoured some sort of a constitutional amendment that would allow seats to be more quickly filled, possibly by the appointment of successors by governors or state legislatures. Mr Baird proposed an amendment that would allow members to name potential successors.

The US constitution permits gubernatorial appointments to replace deceased senators. But it requires that all House members be elected, and backers of the House-passed bill said they want to keep it that way in "the people's house".

Special elections are now held to replace deceased House members, a process that often takes several months in many states. Judiciary Committee Chairman James Sensenbrenner, a Wisconsin Republican and chief sponsor of the bill to expedite election of replacement lawmakers, promised to have Baird's measure sent to the full Republican-led House for consideration.

Sensenbrenner, like many Republicans, predicted Baird's proposed constitutional amendment would fail, but said, "We ought to see who wants to have our replacements be elected or our replacements be appointed."

The House-passed bill goes now for consideration in the Senate, where a constitutional amendment approach has been proposed but not voted on. Sen John Cornyn, a Texas Republican, has proposed that if if a fourth of House members are killed or incapacitated, each state would have the option to hold a special election or permit interim appointments.

Cornyn's amendment would permit for the first time replacement of incapacitated senators. The non-partisan Continuity of Government Commission, created after the Sept 11 attacks, has also urged a constitutional amendment approach and argued special elections would be inadequate.

House Majority Whip Roy Blunt, a Missouri Republican, voiced support of House-passed bill, but said, "I hope the work we do today is never tested one way or the other." -Reuters