Rep. Ron Paul's third White House bid is another long-shot attempt because of lingering questions about his viability in a Republican primary and beyond.
Doubts also exist about the Texas Republican's level of tea party support. The more mainstream presidential candidates have co-opted portions of his fiscal message as they also work to woo grass-roots activists who had been seen as Paul's natural constituency.
It's not clear whether Paul, who on Friday became the only Member to officially join the race, would be a 2012 factor beyond his demonstrated abilities to raise money and score debate points.
The eight-term Congressman's libertarian view of the federal government is considered less fringe now than it was during his 2008 White House bid, following the 2010 rise and subsequent influence of the tea party and an ongoing national fiscal crisis that has focused voters' attention on the $14 trillion federal debt. Yet Paul, 75, is no longer the lone Republican voice to advocate for dramatically reducing the size and scope of government.
The others in the race are better-organized candidates who are likely to be perceived by primary voters as more formidable against President Barack Obama. Rep. Michele Bachmann (R-Minn.), a tea party favorite, could further complicate Paul's prospects should she run, although GOP strategists say the Congressman's support within the conservative activist movement is overblown to begin with.
"Ron Paul voters aren't necessarily tea party people," said a Republican strategist who worked for a GOP presidential candidate in 2008. "He had his own little niche, so he doesn't necessarily impact Bachmann. Plus, Bachmann has the advantage of being the candidate the Christian right gets behind. Paul doesn't."
Paul's social views could be considered liberal. He argued in a debate this month, for example, that government should stay out of the bedroom when it comes to the gay marriage debate. He also favors legalization of drugs.
Ryan Hecker, a Houston Tea Party board member who helped launch www.MyTeaParty.org, said Paul would add an attractive voice to the GOP presidential primary contest, but he suggested Paul might have less appeal with this disparate coalition of political activists than some might think.
"I don't see him becoming the monolithic tea party candidate. There is a certain segment of the tea party movement that likes him, but it's not overwhelming," Hecker said. "I think there is definitely a libertarian-versus-conservative divide there, and there is also a viability issue for those who are contemplating his candidacy."
It is extremely rare for a sitting House Member won the presidency, although former House Members who went on to serve as governor, Senator or vice president have won the office. Paul served in the House as a Republican in the 1970s and 1980s before making his first bid for president in 1988 on the Libertarian ticket. He ran again in 2008.
Vice President Joe Biden waits to conduct a mock swearing-in ceremony with Sen. Brian Schatz, D-Hawaii, in the Capitol's Old Senate Chamber, December 2, 2014. Schatz was sworn in to serve the remainder of his term since he was appointed to the seat after Sen. Daniel Inouye, D-Hawaii, passed away.