From the Politico's Mike Allen and Jonathan Martin:

John McCain stated unequivocally in an interview with Politico Wednesday that he would not pledge to serve only a single four-year term, rejecting a suggestion that some allies believe would allay questions about his age and underscore his non-partisan message of putting country first.

"No," McCain said flatly, "I'm not considering it."

There has been speculation that McCain, 71, could couple a single term promise with a untraditional running mate such as Democrat-turned-Independent Sen. Joseph Lieberman to make the case that he would shove political interests aside and run a consensus-oriented government with the Democratic-held Congress.

McCain didn't say he would serve two terms, he just said he wouldn't pledge to serve only one. But Allen and Martin are right to say that this could affect Lieberman-as-VP speculation. As Rich Lowry wrote, the one-term pledge was one of the few viable scenarios for a McCain-Lieberman ticket.