Jackie Speier, a Democrat and former state legislator, was sworn in after winning a special election to replace Rep. Tom Lantos, who died Feb. 11 of cancer. She must win a June primary and election in November to serve a full term, the San Francisco Chronicle reported.
Some Republican colleagues booed or walked out when Speier criticized President George W. Bush's Iraq policy and presumptive GOP presidential nominee John McCain's support for it.
"The president wants to stay the course and a man who wants to replace him suggests we could be in Iraq for 100 years," she said. "But Madam Speaker, history will not judge us kindly if we sacrifice four generations of Americans because of the folly of one."
Speier said she did not feel like she is replacing Lantos, calling him irreplaceable.
Speier was legal counsel in the 1970s to Rep. Leo Ryan, D-Calif. She was critically wounded in the 1978 Jonestown, Guyana, shooting in which Ryan was killed.