Nearly six in 10 of those siding with Mitt Romney in a new Washington Post-ABC News poll say their vote is primarily “against” President Obama not in favor of the former Massachusetts governor, a testament to how much of Romney’s support is built on opposition to the current occupant of the White House.

By contrast, about three-quarters of Obama’s supporters are voting affirmatively “for” the president.

Romney’s support numbers are similar to those of Massachusetts Sen. John Kerry (D) in 2004 and Obama’s support numbers mirror those of President George W. Bush in his bid for a second term. The 2004 contest was close, but ultimately the “Bush protest” vote was not enough to put Kerry on top.

It remains to be seen whether voting against Obama rather than for Romney will be enough to pave the challenger’s path to victory. Even among top Republicans, however, there’s an acknowledgment that Romney’s greatest strength among many voters is simply that he isn’t Obama.

The American people probably aren’t going to fall in love with Mitt Romney,” said House Speaker John Boehner (Ohio) during a West Virginia fundraiser last week.