President Obama will host Sen. John McCain (R-Ariz.) for a private meeting at the White House on Wednesday.

It will be the first meeting between the president and his 2008 Republican adversary since Obama took office.

The White House said Tuesday night the Oval Office meeting would take place Wednesday afternoon, though there was no indication as to the reason for the meeting, or scheduled topics for discussion.

Obama and McCain sat down for talks at transition headquarters in Chicago after the Democrat's election. The two have crossed paths since then, but not one-on-one; McCain participated in an April 2009 meeting at the White House with leaders of the House and Senate Armed Services committees, and McCain was a participant in the bipartisan healthcare summit a year ago.

In the two years since the election, McCain has emerged as one of the most strident GOP critics of Obama. The Arizona senator has been a foremost critic of government spending, and issues like the repeal of "Don't ask, don't tell" policy banning gays from serving openly in the military. He also tacked to the right on issues like immigration during his 2010 primary.

But McCain has also softened his tone somewhat since the assassination attempt against Rep. Gabrielle Giffords (D) in his native Arizona. McCain praised Obama's response and the speech delivered at a memorial service last month in Tucson.