TOPEKA, Kan. (AP) — Republican Sen. Pat Roberts plans to have an event with a U.S. Chamber of Commerce leader as his race for re-election in Kansas heats up.

The event Monday afternoon is at the Kansas Chamber of Commerce offices in Topeka. U.S. Chamber Senior Vice President Rob Engstrom also is participating.

The Roberts campaign said the national business group would make an announcement but was not more specific.

The 78-year-old Roberts is seeking his fourth, six-year term but is in a tight race with independent candidate Greg Orman. The 45-year-old Orman is an Olathe businessman and co-founder of a private equity firm.

The two candidates had a debate scheduled Wednesday in Overland Park, and Roberts planned to kick off a four-day bus tour Thursday in Wichita with Texas Sen. Ted Cruz.