Topeka ? Republican U.S. Sen. Pat Roberts’ campaign Monday brought a top official from a powerful national business group to Kansas and announced that tea party movement icon Ted Cruz would help launch a four-day bus tour later in the week, with time growing short for the incumbent to save his re-election bid.

The race in GOP-leaning Kansas became a key battleground in the Nov. 4 election as Republicans fight for a net gain of six seats to recapture a Senate majority. The Kansas Democratic nominee dropped out of the race last month, giving independent candidate Greg Orman a better chance of defeating Roberts after the three-term incumbent emerged vulnerable from a tough GOP primary against a tea party challenger.

Orman, the 45-year-old co-founder of a private equity firm, is running as a centrist and touting his business background. The 78-year-old Roberts sought to undercut him on both fronts Monday, holding a news conference Monday in Topeka with Rob Engstrom, senior U.S. Chamber of Commerce vice president. The group has backed Roberts since February.

“The race is fundamentally about which candidate is best positioned to support the business community,” Engstrom said, noting that Roberts has a 92 percent rating with the group.

Orman said in an email Monday to supporters that he’s “laser-focused” on creating jobs. While Roberts’ campaign has brought nationally prominent Republicans — and Roberts said 2012 presidential nominee Mitt Romney will visit Kansas — Orman has held meetings with small business owners.

“The risk-takers and entrepreneurs of America know what’s best for our economy — not career politicians,” Orman said in his email.

A new poll of 636 likely voters from NBC and Marist College, in Poughkeepsie, New York, showed Orman with a 48 percent-to-38 percent lead over Roberts, with 9 percent undecided. The poll was conducted from Sept. 27 to Oct. 1, with a 3.9 percent margin of error.

Orman has said he’ll caucus with whichever party has a clear Senate majority and could play kingmaker if neither does. He contributed to Obama’s first presidential campaign, but he’s been registered with both parties and has said he eventually became disappointed in both.

The Roberts campaign also released an endorsement Monday from Cruz, a Texas senator who precipitated last year’s partial, 16-day federal government shutdown over his opposition the federal health care overhaul. Cruz is scheduled to be in Wichita Thursday for the kickoff of the Roberts bus tour, which will stop in 11 communities.

Orman campaign manager Jim Jonas said inviting Cruz to Kansas shows that Roberts “is an enthusiastic participant in a broken system.”

The U.S. Chamber is backing Roberts despite Orman’s business background and a stance on illegal immigration that aligns relatively well with the group’s.

Orman, like the U.S. Chamber, says it is impractical to deport millions of immigrants and they should be allowed to stay if they register with the federal government, pay fines, hold down jobs and avoid further criminal activity. Roberts has labeled that position “amnesty” and denounced it.

Engstrom said the Chamber is looking at the totality of the candidate’s records, not just a single issue. He also joined with Roberts in accusing Orman of trying to hide liberal Democratic leanings.

“He can say he’s an independent,” Engstrom said. “I could say I’m a unicorn, but I’m not a unicorn.”

But Jonas said of voters, “They want someone with a real record of solving problems, not playing tired political games.”