Washington (CNN) - The nation's largest tea party political action committee is planning a major push this September for Mitt Romney and other Republicans with what will be their "longest" cross country bus tour since the movement began in 2009, the group said Wednesday.
The Tea Party Express will mount its eighth nationwide tour – titled "Winning for America" - in the last two weeks of September and the first week of October, according to chief strategist Sal Russo.
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The circuit will begin in Florida and hit several other battleground states, including Pennsylvania, Ohio, North Carolina, Virginia, Colorado, and Nevada. Other stops are planned for Wisconsin, Michigan, Montana, Missouri, and Georgia.
"It's going to be our longest tour," Russo said. "We're covering so much ground…it looks like a W across the country."
The group intends to invite presumptive GOP presidential nominee Romney to participate in the tour. Russo stressed that the invitation has not yet been made, though he hopes Romney will accept.
The intention to invite Romney is a sign that tea party activists are increasingly warming to the former Massachusetts governor's candidacy. Many tea partiers have long viewed Romney as not sufficiently conservative – a claim Romney's supporters have long beat back. Yet most activists openly back Romney, whether willingly or begrudgingly, because of fierce opposition to President Obama.
The tour will be the first test of tea party power ahead of a presidential election. In 2010, the movement saw mixed success: helping to flip the House into Republican hands but losing coveted Senate races in Alaska, Delaware and Nevada. Since then, tea party activists have also wrecked political aspirations of other establishment Republicans in other parts of the country.
While stressing that tour details are still being worked out, Russo discussed its logistics, goals and aim.
As in past Express bus tours, the upcoming one will include two to three buses carrying staffers and supporters from rally to rally. Russo stressed that tour stops have been planned for maximum political effect: to not only help Romney but also Republican candidates for the Senate and House.
For example, the Express' Pennsylvania stops are planned to help put that state's 20 electoral votes in Romney's column. But it will also aim to help elect Republican candidates to the House as well as GOP U.S. Senate candidate Tom Smith in his race against Democratic Sen. Bob Casey. The Express has endorsed Smith. But their attempts appear to be futile: Casey has led Smith by double-digits in recent polls.
While praising Smith, Russo added: "I think [Pennsylvania is] going to be a big state for Romney. I think they're going to put a lot of resources in there."
In North Carolina, the Express will rally supporters for Romney as well as to defeat Democratic Reps. Larry Kissell and Mike McIntyre.
The Express' stops in other states are also designed to help Romney as well as other GOP candidates. The highlight in Virginia will be the Senate race between former Virginia Gov. Tim Kaine and former Sen. George Allen; in Florida it will be the race between Democratic Sen. Bill Nelson and GOP Rep. Connie Mack, who's expected to win his party's senate nomination in the state.
"We can play a bigger role in U.S. Senate races than we can in presidential races," Russo said. "So we're trying to be in states which are going to be competitive in the Senate as well as in the presidential race. And when we can, we try to go in the areas of the state where there are competitive House races."
Though many tea party activists were openly hostile to Romney's bid during the GOP primaries, there were also signs of a thaw. For example, last year on Labor Day in New Hampshire, Romney headlined his first major tea party rally.
But getting the tea party's stamp of approval carries risks. The movement remains popular with many conservatives and has a proven track record in energizing them. Yet many independents are turned off by the tea party, potentially turning some of them away from Romney.
Meanwhile, on Wednesday the Express also announced its supporters' choice for Romney's running mate.
In a survey of over 8,000 supporters, Florida Republican Sen. Marco Rubio was the favorite, with 66% of the vote.
"It is not a big surprise that Marco Rubio is the favorite candidate of the tea party for the vice-presidential nod," Express Chairman Amy Kremer said in a statement. "He ran as a strong fiscal conservative, and he has delivered with his record in the U.S. Senate for the last two years. The only surprise is that he led the other excellent candidates by such a wide margin."
Those other candidates are: House Budget Chairman Paul Ryan, who garnered 49.9% of the tea party VP vote, Florida Rep. Allen West, with 46.8%, former Pennsylvania Sen. Rick Santorum, with 44%, former Alaska Gov. Sarah Palin, with 41%, and Minnesota Rep. Michele Bachmann with 40.9%.
Ohio Sen. Rob Portman, Louisiana Gov. Bobby Jindal and former Minnesota Gov. Tim Pawlenty – three men believed to be leading vice presidential contenders – ranked low in the Tea Party Express results.