Maryland Gov. Martin O'Malley shakes hands with a supporter at the Mach 1 signing of Maryland’s same-sex marriage law. (Linda Davidson — The Washington Post)

Host David Gregory previewed the show and its topics during an appearance Friday morning on MSNBC.

O’Malley has had a lot of say lately on both subjects. He issued a statement of support almost immediately Wednesday after news broke about President Obama’s embrace of same-sex marriage.

O’Malley signed Maryland’s same-sex marriage law in March. It is widely expected to be petitioned to the November ballot, where voters will get a say before it is scheduled to take effect in January.

“I think the president’s statement ... is probably the most significant advancing of our cause since the bill-signing,” O’Malley told the Post’s Jonathan Capehart on Wednesday. “This is an issue that is moving very quickly in the hearts and minds of people throughout our country, and that is certainly true here in the state of Maryland.”

As chairman of the Democratic Governors Association, O’Malley has also talked up Obama’s 2012 reelection prospects and those of other members of his party in previous television appearances.

While the appearances have raised O’Malley’s national profile, he has drawn some flak back in Annapolis for spending too much time on national politics.

Reince Priebus, the chairman of the Republican National Committee, is scheduled to appear with O’Malley on Sunday’s broadcast.