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The Republican presidential candidates who campaigned, debated and otherwise scrapped for months to stand alone in Tampa are essentially all here -- with Mitt Romney at center stage and his former rivals both inside and outside the party tent.

Former Pennsylvania Sen. Rick Santorum was Romney's toughest opponent but will have the most prominent role, speaking Tuesday night on the convention stage.

Santorum gradually has gone from Romney rival to surrogate, and as recently as Monday penned a full endorsement in The Hill newspaper of the Romney-Paul Ryan ticket that also slammed President Obama's policies as a "path to decline."

The rest of the primary pack is milling about the convention perimeter, assuming a range of roles -- from gadfly (Ron Paul) to professor (Newt Gingrich) to rabble-rouser (Michele Bachmann and Herman Cain).

Though former candidate Gingrich does not have a speaking role, the former House speaker and ex-college professor was hosting a series of public policy workshops for delegates at hotels around the convention compound -- starting Monday with one about the economy and Medicare.

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    Gingrich said at the start of the four scheduled workshops -- known as "Newt U" -- that they will provide "fact-based solutions to the economy." And like Santorum, his mission appears as much about defeating Obama as backing Romney, the GOP primary victor.

    Gingrich employed, on Romney's behalf this time, the kind of terse zingers that used to be reserved for the presumptive nominee.

    "Some people write about the (bad economy being) the new normal. Baloney," Gingrich said. "It's the Obama normal. And there's a solution to it -- fire Obama."

    Texas Rep. Ron Paul is fulfilling his role as the party outsider -- having held a rally Sunday several miles from the Tampa Bay Times Forum in which he told a crowd of roughly 8,000 rowdy, libertarian-minded attendees that the Republican establishment was "failing" the country and that the party would eventually drift into his "tent."

    "We'll get into the tent, believe me, because we'll become the tent eventually," the 77-year-old congressman said. "Once they know we are the future they will know about us."

    Paul is supposed to be honored at the convention with a video tribute, despite attempting to upstage Romney and the entire convention by jockeying for delegates long after exiting the race.

    Romney running mate Paul Ryan, playing down the tensions, told Fox News on Monday that he thinks Paul's supporters will eventually be "very comfortable" with the ticket.

    Also Sunday night, before the official start of the convention, Tea Party-aligned former candidates Cain and Bachmann helped lead a rally of several hundred people inside a Tampa-area church, with Bachmann asserting the movement is still very relevant.

    "We are not an unwanted second-class political party," she told the Tea Party crowd. "We are the conscience of the United States Constitution. And we won't apologize for that."

    Bachmann also attacked Obama, calling him a Socialist before telling those in attendance, "I want you to know how incredibly successful you have been as a movement."

    One of the few ex-candidates missing in action this week is former Utah Gov. Jon Huntsman, who has largely let his daughters do the talking, including one recently taking to Twitter to knock down rumors that her father will speak next week at the Democratic National Convention.