Despite Donald Trump's consistent lead in most polls and Ben Carson's lead in Iowa polls, another Republican presidential candidate is increasingly being called a front-runner by the press.

Ross Douthat of the New York Times recently wrote that Florida U.S. Senator Marco Rubio may win the nomination through process of elimination because "no major party has ever nominated a figure like Trump or Carson."

NBC News reported that Rubio's rise is attributed to "declining Republican optimism" about Jeb Bush, with whom Rubio shares several policy positions. Fox News media critic Howard Kurtz also speculated whether Rubio might be the last candidate standing. Republican strategists such as Gary Marx argue that Rubio could emerge as a front-runner by uniting differing party factions.

The idea of Rubio as a front-runner is not new, but how do those prospects shape up?

Although often hailed as "the future of the Republican Party," Rubio is hobbled with low fundraising numbers, especially from small contributors - a sign of grassroots support. According to OpenSecrets.org, about 20% (roughly $3 million) of his funds come from small individual contributors. Sen. Rand Paul, whose polling numbers are about half of Rubio's, has raised almost $4.5 million from small contributors.

wealth. In addition to the senator's well-known hawkish foreign policy, his support of a bill this summer to block states from loosening online gambling rules was considered another appeal for Adelson's money.

Multiple news outlets also reported over the weekend that billionaire New York investor Paul Singer was investing in Rubio because

Drudge also reported over the weekend that Singer lobbied in favor of the immigration reform effort Rubio spear-headed in 2013. The political fallout from the GOP led Rubio to distance himself from the program that has often been called amnesty for illegal immigrants. Public knowledge of Singer's financial support could renew scrutiny of Rubio's past backing of immigration reform and raise questions about the sincerity of the latter's policy shift.

Despite the praise in the press and his presumed securing of wealthy benefactors, Rubio has further liabilities. First, his current poll numbers are actually lower than they were when he announced his candidacy in April. In the spring, Rubio's numbers were around 15%, compared to approximately 10% now.

Second, although receiving generous donations from Adelson and others would boost Rubio's campaign, largesse is not necessarily an indicator that the senator is or will be the front-runner. Jeb Bush's consistent lead in overall fundraising numbers has not kept him out of the single digits in national polls. Adelson poured $15 million into Newt Gingrich's campaign in 2012 who, aside from winning the South Carolina primary, never put up a serious challenge for the nomination.

The Iowa Caucuses are still three months away, so the Republican race could still take a new shape. Rubio could emerge as the front-runner or the nominee, but several obstacles remain in his way.

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