Posted Thursday, October 18, 2012 --- 6:45 a.m.

MILWAUKEE (AP) -- Three Republican senators will join Senate candidate Tommy Thompson on the campaign trail in Milwaukee.

Sens. Ron Johnson of Wisconsin, John McCain of Arizona and Lindsey Graham of South Carolina are scheduled to join the former governor at a news conference Thursday morning.

McCain and Graham were already in town to host a fundraiser for Thompson on Wednesday night.

Thompson is locked in a tight race with Democrat Tammy Baldwin. A Marquette University Law School poll Wednesday showed the race tied, with Thompson up 46 percent to 45 percent. The gap was within the poll's margin of error.

But Baldwin enters the final weeks of the campaign with the cash advantage. She says she started October with $3.5 million, while Thompson says he had nearly $2 million cash on hand.

Copyright 2012. The Associated Press.