It’s go time at CPAC – and that means it’s crunch time for former Massachusetts governor Mitt Romney (R).

The annual Conservative Political Action Conference holds its second day of events today, and three of the four GOP White House hopefuls — Romney, former House speaker Newt Gingrich (Ga.) and former senator Rick Santorum (Pa.) — address the crowd at the Marriott Wardman Park in Washington.

Santorum is up first at 10:25 a.m., followed by Romney at 12:40 p.m. and Gingrich at 4:10 p.m. Rep. Ron Paul (R-Texas) will not attend; his son, Sen. Rand Paul (R-Ky.), spoke on his behalf Thursday afternoon.

The big question heading into the day is what kind of reception Romney will receive from conference attendees, many of whom on Thursday expressed support for Romney’s rivals and also voiced resignation that the former Massachusetts governor is on track to clinch the GOP nomination.

In an interview on Fox News Channel’s “Hannity” Thursday night, Romney previewed his CPAC speech and defended his appeal among conservatives.

“First of all, I’d note that I won among conservatives in New Hampshire; I won solidly among conservatives in Florida; won among conservatives in Nevada; and have the most delegates in this race, so I wouldn’t say that I haven’t been able to get good support from conservatives,” Romney told host Sean Hannity.

He said that his speech will touch on his time as governor, including his economic record as well as “some of those things [that] get hidden over time” such as his handling of a contraception controversy similar to the one playing out now on the national stage. National Democrats and some of Romney’s GOP rivals have sought to use the episode against him on the campaign trail in recent days.

“The legislature passed a bill for a morning-after pill, insisted that Catholic churches provide this to their employees and universities and hospitals,” Romney said Thursday night. “I vetoed that bill. I was one of those that stood up and fought against the intrusion on religious liberty in my state.”

He also said he will talk about his record on the issue of gay marriage.

“Obviously, the supreme court in my state began the process of providing for same-sex marriage,” Romney said. “I led the charge to put in place an amendment that would reverse their decision, and we missed by one vote in the legislature to be able to proceed with that amendment.”

That Romney intends to talk about social issues as well as economic matters is a sign that he’s taking Santorum’s surge seriously. Some Romney supporters at campaign events in recent days have suggested that focusing more on social issues is a smart strategy for Romney, particularly as the contraception battle becomes increasingly heated.

But Romney also faces a risk in doing so — namely, his raising of the issue could remind some voters of his more-moderate views during his years as governor.

CPAC isn’t the only big test Romney faces on Friday: Following his summit address, he heads for Maine, where he is set to take questions from voters for the first time in a month.

We’ll be with Romney on the trail today and tomorrow when Maine announces its caucus results, and our colleagues at The Fix will be liveblogging the goings-on at CPAC in Washington. Follow us at PostPolitics.com and on Twitter at @2chambers for up-to-the-minute updates.

A closer look at today on the trail (Courtesy of candidate schedules and the PBS NewsHour Political Calendar; all times Eastern):

7:45 a.m.: Mitt Romney delivers remarks at the Northern Virginia Technology Council/CEA Presidential Series in Reston, Va.

9 a.m.: Mike Huckabee addresses CPAC.

10:10 a.m.: Bob McDonnell addresses CPAC.

10:25 a.m.: Rick Santorum addresses CPAC.

12:40 p.m.: Mitt Romney addresses CPAC.

1:30 p.m.: Rick Santorum holds a meet-and-greet at CPAC.

4:10 p.m.: Newt Gingrich addresses CPAC.

5:15 p.m.: Mitt Romney holds a town hall in Portland, Maine.