In the wake of Mitt Romney's romp through five more Republican primary states, Newt Gingrich appears to be poised to leave the presidential race.

Sources close to the campaign told Politico that Gingrich is set to suspend his campaign in a Wednesday afternoon announcement, and that it is highly likely he will also endorse Romney.

Gingrich has been defiant throughout the contest, declaring his intention to continue his campaign until the Republican National Convention even as he has dropped far behind in the delegate count and seen his campaign become saddled with millions in debt. But the former Speaker of the House suggested in a speech to supporters that he was prepared to concede to the reality that Romney is all but certain to be the Republican party's presidential candidate.

I want you to know over the next few days, we're going to look realistically at where we are at in the campaign, Gingrich told a meager crowd at a Tuesday night rally.

Gingrich also called on Republicans to rally behind Romney's candidacy, moving away from the combative rhetoric that has underpinned an often bitter campaign in which he has repeatedly attacked Romney for his record.

I want you all to understand that Gov. Romney is going to have a very good night and it is a night that he has worked hard for, for six years, Gingrich said. And that if he does end up as the nominee, I think every conservative in the country has to be committed to defeating Barack Obama and let's be very clear about this.

The former Speaker of the House went further on Wednesday, saying in a speech to the Gaston County GOP in North Carolina that it's pretty clear Governor Romney is going to be the nominee. 

I think you have to at some point be honest with what's happening in the real world, as opposed to what you'd like to have happened, Gingrich said. Governor Romney had a very good day yesterday. He got 67 [percent] in one state, and he got 63 in other, 62 in another.

Gingrich surged into contention in December and sent tremors through the race when he decisively won the South Carolina primary, suggesting that he could capture the rural, working class and Tea Party-affiliated voters who had eluded Romney. But his campaign faltered from there, and his only victory since was in his home state of Georgia.

The possibility of Gingrich leaving the race could be a boon for Romney's campaign coffers, as Sheldon Adelson -- the billionaire casino magnate who has helped sustain Gingrich's campaign by pouring millions into the pro-Gingrich Winning Our Future Super PAC -- has hinted that he would throw his support to Romney should Gingrich drop out.