LAKE CHARLES, La. -- Newt Gingrich’s tortured, long-shot path to the Republican presidential nomination relies on a contested GOP convention where no candidate has a majority of delegates before it starts.

Among the many hurdles Gingrich must overcome to sustain his campaign is one crucial qualification to get on the ballot at the August convention in Tampa -- Gingrich must have the most delegates from five states already in his corner.

Of 33 contested states and territories, the former U.S. House speaker from Georgia has won only the South Carolina and Georgia primaries thus far.

According to Republican National Committee Rule 40(b): “Each candidate for nomination for President of the United States and Vice President of the United States shall demonstrate the support of a plurality of the delegates from each of five (5) or more states, severally, prior to the presentation of the name of that candidate for nomination.”

The rule means Gingrich does not necessarily have to win five states, but he does have to amass the most delegates in five states and prove it before the convention starts. His aides argue that Gingrich can do so by picking up delegates who are not tied to the results of a state’s primary or caucus.

Outside observers cast doubt on the strategy.

“There doesn’t seem to be a realistic chance of that,” said Republican strategist Doug Heye, a former RNC communications director. “It’s almost grasping for anything.”

Gingrich is spending the week in Louisiana ahead of Saturday’s primary, and he has traditionally performed better in the South. But his campaign is not expecting a win after former U.S. Sen. Rick Santorum of Pennsylvania topped Gingrich on March 13 in Alabama and Mississippi. Gingrich is not holding a primary night party in Louisiana, instead traveling to Pennsylvania on Saturday to speak at a conference of conservatives.

State wins are no longer the calculus of the Gingrich campaign, even down to the candidate’s speeches, as across Louisiana he has promised crowds not victory but delegates Saturday.

The Pennsylvania trip provides yet more evidence: The state’s 72 delegates are not bound by the results of its April 24 primary, and Gingrich will be taking his pitch directly to potential delegates at the Pennsylvania Leadership Conference.

Gingrich adviser Randy Evans, an attorney at McKenna Long & Aldridge in Atlanta, keeps track of the RNC’s labyrinthine delegate selection process with a series of spreadsheets. He said there is a path to securing a plurality of delegates in five states.

“Obviously, we’d much prefer to win five states," Evans said, "but the idea that it’s a legal prerequisite is a falsehood.”

He pointed to Louisiana, Pennsylvania and Texas as opportunities to win major troves of delegates. He also raised the prospect of winning the District of Columbia, where the winner gets all 19 delegates. Santorum is not on the ballot there, and Evans estimates the turnout will be only 6,000. But former Massachusetts Gov. Mitt Romney is heavily favored in the district, given the affluent demographics of Republican voters there.

Evans said the campaign has identified about a dozen states where delegates are pledged at county and state conventions -- long after the primary or caucus vote -- and where the Gingrich campaign can try to peel away delegates.

Evans said there are several different strategies for wooing unpledged delegates, most of whom have yet to be selected.

One consideration, Evans said, is “simply, what are the dynamics when we get to July?”

If Santorum drops out by then, all his delegates would become unbound, though at this point it is hard to imagine him exiting before Gingrich. Santorum has more victories, delegates and money, according to campaign finance reports.

Both badly trail Romney and are under increasing pressure to smooth the path to his nomination. But both campaigns remain hopeful that they can deny Romney the clinching 1,144 delegates by the time the convention arrives.

Following Romney’s wide victory in Tuesday’s Illinois primary he led the field with 563 delegates, with Santorum claiming 263, Gingrich at 135 and U.S. Rep. Ron Paul of Texas with 50, according to an Associated Press tally.

Paul also would have trouble getting on the Tampa ballot, as he has not won a state, though he appears to be angling for a chance to help shape the GOP platform more than contesting the convention.

For Gingrich, even making his way onto the Tampa ballot would require a stunning turnaround or organizational masterwork. The possibility of that, Heye said, appears dim for a candidate who thrived on debates -- there are no more GOP contests scheduled -- and who was too poorly organized to make the ballot in the state where he lives, Virginia. (Santorum also was not on the Virginia ballot, which required an unusually high 10,000 verified signatures.)

“There have been so many scenarios and things that have happened, it’s hard to make a real prediction,” Heye said. “But the path for Gingrich to be a viable candidate at the convention just doesn’t appear to exist. That’s the challenge that he faces.”