"I'm not discussing the vice presidential vetting process," the governor told WTOP. "You can address those questions to the Romney campaign."

For those trying to read the vice presidential tea leaves, McDonnell's sudden silence could indicate that the popular governor is moving up the short list. With Virginia's 13 electoral votes very much up for grabs — and a crucial component of a Romney path to the presidency — the popular governor could be a good strategic pick.

Speculation has been rampant in recent weeks about who Romney might choose. Last week, a report from ABC News indicating the Romney campaign had not requested vetting documents from Sen. Marco RubioMarco Antonio RubioGOP group calls on Republican senators to stand up to McConnell on election security in new ads What the gun safety debate says about Washington Trump moves forward with F-16 sale to Taiwan opposed by China MORE (R-Fla.) led many to question whether the freshman lawmaker had fallen out of favor.

Romney was dogged by questions about the process on the trail, eventually telling Fox News that the reports were untrue and Rubio was being vetted.

"There was a story that originated today apparently at ABC based upon reports of supposedly outside unnamed advisers of mine. I can't imagine who such people are. But I can tell you this: they know nothing about the vice presidential selection or evaluation process," Romney said. "There are only two people in this country who know who are being vetted and who are not: And that's Beth Myers and myself. And I know Beth well. She doesn't talk to anybody. The story was entirely false. Marco Rubio is being thoroughly vetted as part of our process."

McDonnell is appearing on behalf of the Romney campaign at a fundraising lunch Tuesday in Washington. Romney campaigned earlier in the day in Salem, Va., and will appear in the Washington suburbs on Wednesday.