Washington (CNN) -- Democratic Rep. Diane Watson of California will retire at the end of the year rather than run for re-election, three Democratic sources said Wednesday.
Watson, 76, represents California's 33rd district, which includes parts of West Los Angeles and Culver City. The four-term representative won a special election in 2001 and re-election in 2002, 2004, 2006 and 2008.
The district is considered overwhelmingly Democratic.
Watson has won at least 80 percent of the vote in each of her re-election contests. Barack Obama took the district by 75 percent in the 2008 presidential election, and John Kerry won the district by 67 percent in the 2004 presidential contest.
Watson's congressional office said she has scheduled a news conference for Thursday but would not confirm the retirement, first reported by CQ-Roll Call.
But Democratic sources confirmed Watson's retirement hours after Republican Rep. Vern Ehlers of Michigan announced that he would not run for re-election in November.
Ehlers becomes the fifth House Republican to retire rather than run for re-election. Eleven other House Republicans are making bids for higher office rather than seek re-election.
Watson will become the seventh House Democrat to retire at the end of the year rather than run for re-election but the first from a district considered safe for the party.
Separately, Democratic Rep. Robert Wexler of Florida stepped down at the beginning of the year to head up the Center for Middle East Peace.
A special election will be held April 13 for the seat, which is considered safe for Democrats.
Six other House Democrats are running for statewide office rather than re-election in November.
A special election will also be held this year for the seat of Democratic Rep. John Murtha of Pennsylvania, who died Monday.
CNN's Paul Steinhauser, Mark Preston and Deirdre Walsh contributed to this report.