Tim Pawlenty has worked tirelessly in Iowa, but so far there hasn’t been much payoff, Bloomberg News says.

And that means the wisdom of putting his presidential hopes  so firmly in the hands of the neighboring Iowans may be tested next month, at the Republican Party’s Straw Poll.

“I think he’s got to win the straw poll, or he’s going to be in tough shape,” Doug Gross, an Iowa Republican, told Bloomberg. “This is everything for him. For that reason, the straw poll is going to be something that is highly watched.” Gross ran Mitt Romney’s 2008 statewide campaign and is unaligned now.

He also predicted that finishing well behind Bachmann could “force Pawlenty out of the race” because “there are some Minnesota Twins fans in Iowa, but not enough.”

Pawlenty told Bloomberg’s John McCormick that he’ll spend half of July in Iowa, preparing for the straw poll:

“We don’t need to win it, but we need to show progress,” he said in an interview yesterday at his campaign headquarters in Urbandale, Iowa. “We view the straw poll as the kickoff to the real, full campaign season.”

Whatever his finish in the straw poll, Pawlenty said, he has no plans to leave the campaign. In the past, some candidates have dropped out after finishing below expectations.

“We don’t plan on being one of those,” he said. Referring to a weed and grass killer, he said, “They’re not going to put the political Roundup on us.”