WISCONSIN DELLS, Wis. -

Mitt Romney is the presumptive GOP nominee for president at next week's Republican National Convention, but a group of so-called "upset GOP members" are pushing another candidate.

A group called Earthquake Movement has started a campaign for Sarah Palin for president.

The group is behind a number of new digital billboard ads that started their rotation this past weekend in the Wisconsin Dells area. The messages are aimed at GOP delegates, urging them to nominate Palin for president -- not Romney.

In a statement, the group said, "We are finding a lot of unhappy Republican voters. They feel like the RNC is not listening to them, and based on voter turnout in the primaries and what we are hearing from conservative Americans, they want her to emerge from the convention as the nominee."

The group also said it's upset that Palin was not offered a prime-time speaking spot at the convention.

Sauk County Republican Party Chairman Tim McCumber said that while the tactic is creative, it's just not going to work.

"I think the signs they've put up in the Dells clearly show they don't understand the process," McCumber said. "We had a primary here. Wisconsin voters, in an open primary, came in and selected our candidate. Our delegates will go down, under our rules, and vote for that candidate."

The group said it has placed similar ads in a handful of other markets. The group is careful to say on its ads that the billboards are not endorsed by Palin.

The group said it has already reached out to 1,000 delegates in all parts of the country, providing them with literature about Palin and reasons the group feels she should be nominated.

McCumber said that, especially in Wisconsin, he doesn't expect the tactic will work. He said there's just too much excitement, on the state level, about U.S. Rep. Paul Ryan being chosen as Romney's running mate.

The convention itself will take place in Tampa, Fla., Aug. 27-30.