(CNN) – Republican Rep. Kevin McCarthy of California endorsed Republican presidential candidate Mitt Romney Monday.
McCarthy, the House majority whip, will also serve as a statewide chair for Romney's efforts in California, the campaign announced.
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In his statement, McCarthy said Republicans "need to unite" around a candidate Romney.
"After a long and grueling primary, it is clear that Mitt Romney is the best candidate to face President Obama and fix the mess of his one and only term," McCarthy said.
The news came one day after a new poll indicated Romney leading his Republican primary rivals by double digits, ahead of California's June 5 primary. According to the USC Dornsife/Los Angeles Times poll, Romney received 42% support from registered Republican voters, followed by Rick Santorum's 23%, Newt Gingrich's 12% and Ron Paul's 10%.
However, President Barack Obama significantly beat his potential Republican challengers in hypothetical general election match-ups. He led Romney, 57% to 36%, Santorum, 61% to 32%, Gingrich, 62% to 30% and Paul, 59% to 31% among all registered voters.
Obama captured The Golden State in the 2008 election with 61.1% of the vote to then-GOP nominee Sen. John McCain's 37.1%.
The poll surveyed 1,500 registered voters in California by phone between March 14 and March 19 with an overall sampling error of plus or minus 2.9 percentage points.