ABC News’ Amy Walter reports Although the focus has been on liberal Democratic opposition to President Barack Obama’s tax cut deal, the reality is that he doesn’t need that many Democrats to vote with him in order to get his compromise bill – which easily cleared a legislative hurdle in the Senate this afternoon – through the House. Instead, it’ll be up to the Blue Dogs and New Democrats, those moderate Democrats who suffered the most significant losses to their ranks in 2010, to help carry this bill over the finish line. Back in September, a group of 31 moderate Democrats sent a letter to Speaker Nancy Pelosi and Majority Leader Steny Hoyer urging them to offer legislation that would extend all of the Bush tax cuts. These members represented a significant road block to those Democrats, including President Obama, who wanted to vote on a bill that would have including just those tax payers who made under $250,000/year. There was also the concern among some Democratic strategists that forcing a vote on taxes would be politically risky for these already vulnerable members. FWIW, 18 of those 31 incumbents lost re-election this November. The White House was quick to highlight this intra-caucus conflict when defending their decision to cut a deal with the Republican leadership. ABC’s Jake Tapper reported on this push back last week. “We wanted a fight, the House didn't throw a punch," a senior White House official told ABC News, "The House wouldn't vote before the Senate, and the Senate was afraid they'd lose a vote on it." According to the Hill’s Michael O’Brien, White House Communications Director Dan Pfeiffer told liberal radio host Bill Press last week that “he [Obama] and the White House, frankly, urged the House and Senate to hold votes on this before the election. But they didn't do that, in part because there's not unanimity in the Democratic Caucus on this." Yet, with many liberal Democrats threatening to vote against the latest compromise bill, these moderate Democrats, including many who won’t be coming back to Congress in 2012, may once again hold the key to the success of this latest tax compromise. Despite discontent among some conservative Tea Party types like Rep. Michelle Bachmann and Sen. Jim DeMint for this bill, the Republican House conference is expected to stay relatively unified in its support for the Senate bill. While not all 178 GOP members are expected to support the bill, the expectation is that fewer than 100 of the Democratic caucus’ 258 members would be needed to pass the bill. Furthermore, moderate and Blue Dog Democrats who were defeated in 2010 may still have some political calculating to do. If they are thinking about a future in politics they’ll probably want to be on record supporting a bill that cut taxes. In fact, any opportunity to support something that liberals dislike would be an attractive option for many of these folks.