WASHINGTON: Presumptive Republican nominee Mitt Romney and Rick Santorum met Friday to do some fence mending after a bitter campaign, but Romney said he is not expecting his former rival's formal backing just yet.

“I don't think we have plans for an endorsement today,” Romney told Fox news when asked about the private tete-a-tete in Pittsburgh, but he added that “I think all the Republicans will come together and support my candidacy.”

The two Republican stars jousted for months on the campaign trail over who was the truer conservative, and it got heated on several occasions, with ex-senator Santorum accusing Romney of tacking to the right in order to win over core conservatives, with whom Santorum has tremendous sway.

The pair met alone in the office of senior Santorum strategist John Brabender, who said there was no formal agenda for their talk. “A lot of it will be a casual conversation,” he told AFP before the meeting.

Brabender dismissed the possibility that Santorum would emerge from the talks and immediately endorse his former rival, stressing that there would be no negotiations Friday over a possible cabinet post in a Romney presidency.

“I can assure you there won't be any discussion on a position on his team,”he said. “But there will be some discussion of issues that the senator is passionate about.”Arch-conservative Santorum spoke repeatedly at campaign events about social themes like abortion and gay rights, two bedrock conservative issues on which Romney has changed his position over the years.

When Santorum dropped out of the race April 10 after a surprisingly strong grass roots campaign that began last year in a pick-up truck, he did not mention Romney's name.

But the Republicans must close ranks if they want to keep President Barack Obama from winning re-election in November. Two weeks ago on CNN Santorum sidestepped efforts by host Piers Morgan to get him to endorse Romney, but said a Republican win in November was paramount.

“It's very clear that he's going to be the Republican nominee,” Santorum said.

“I'm going to be for the Republican nominee. We're going to do everything we can to defeat Barack Obama.”

Experts have spoken of lingering bad blood between the two Republicans, and Democrats were giddy Friday in using Santorum's own words against Romney, a millionaire former businessman.

Democratic National Committee communications director Brad Woodhouse cited Santorum's campaign comment in which he said “if Mitt Romney's an economic heavyweight, we're in trouble, because he was 47th out of 50 in job creation in the state of Massachusetts when he was governor.”

Newt Gingrich, a diehard challenger for the Republican nomination, officially quit the campaign this week and endorsed Romney.

Libertarian-leaning congressman Ron Paul remains in the race but he has no chance of defeating Romney.