Virginia Gov. Bob McDonnell (R) will not endorse Newt Gingrich at Thursday's joint appearance, a spokesman told The Hill on Wednesday.

McDonnell, who has openly expressed interest in being vice president, will join Gingrich at a Richmond, Va., event for the Republican Party of Virginia on Thursday. But McDonnell spokesman Tucker Martin said that he while he likes and respects Gingrich, he won't endorse him.

"The governor knows the Speaker very well, and he is actually a Virginia voter," Martin said. "The governor believes the Speaker is running an impressive campaign that is focused on big ideas for the future. That said, he continues to believe a current or former governor would make the best nominee for our party. Governors have to balance budgets, exercise executive leadership and manage the governments of their respective states. They must make tough decisions every day. Those experiences provide, in his opinion, very good and necessary preparation for the Oval Office."

McDonnell has said for months he wanted a governor to be president. He would be a major endorsement coup, as a popular governor of a key swing state who Republican insiders had hoped would run for president himself. McDonnell is close with both Rick Perry and Mitt Romney, and has praised both former governors.

The popular Virginia executive has appeared with Perry, Romney and Jon Huntsman when they've held events in his state.

Martin said that McDonnell had not decided whether he will endorse a candidate.

"Gov. McDonnell is continuing to evaluate the field and determining if he will make an endorsement in this race," he said.

Gingrich's Virginia trip comes as an unusual time. Most of the other presidential candidates have zeroed in on the early-voting states of Iowa and New Hampshire. But he was at risk of missing Virginia's ballot. The campaign announced earlier on Wednesday that he did have enough signatures to qualify for the ballot, after Gingrich said earlier in the week that they were "scrambling" to get on it.