Rep. Michael McMahon (D-N.Y.), in a move that reflects the whims of his district, on Tuesday endorsed New York Mayor Michael Bloomberg (I) for re-election over the Democratic nominee, city Comptroller William Thompson.McMahon became the second member of the all-Democratic New York City Congressional delegation to back Bloomberg, joining Rep. Gary Ackerman (D). Other prominent Democrats, including Rep. Carolyn McCarthy, who represents parts of suburban Long Island, have also endorsed him.“Mayor Bloomberg is an independent voice who puts New Yorkers first, not partisan politics,— McMahon said in a statement. “As New York City’s newest Member of Congress I have partnered with Mayor Bloomberg on securing millions of dollars in federal funding to put New Yorker’s back to work, money for homeland security and better transportation. I have been impressed by his leadership and dedication to promoting New York City.—While many New York Democrats praise Bloomberg, who is heavily favored to win a third term on Nov. 3, McMahon’s endorsement is also a reflection of political reality. He represents the most conservative district in the city — the only district that voted for Sen. John McCain (R-Ariz.) in last year’s White House election — and Bloomberg is expected to rack up mammoth vote totals there.McMahon won the 13th district seat, which covers all of Staten Island and most of south Brooklyn, fairly easily last year following a scandal involving his predecessor, former Rep. Vito Fossella (R). But the freshman Democrat could be heavily targeted by Republicans next year, and he has often kept national Democratic leadership at a distance.Michael Allegretti, a former Bloomberg aide, is the only Republican to have expressed an interest in running for McMahon’s seat.Bloomberg, a billionaire business publisher, has had a circuitious political history. A former Democrat, he became a Republican to run for mayor in 2001 and was elected twice on the GOP line. But in 2007, he became an Independent, prompting speculation that he was looking to launch a third-party bid for president in 2008. A White House run never materialized, and Bloomberg instead worked to reverse the city’s term-limit laws so he could seek a third term. While he remains an Independent, he has been cross-endorsed by the GOP and will appear on the Republican line this November.