J.D. Hayworth is a voluble man who wants people to know where he stands. One recent day, he was standing a dozen miles from the porous Mexican border -- the problem he hopes will catapult him past incumbent John McCain (R-Ariz.) into the U.S. Senate.

"If you enforce the law, people will obey the law," Hayworth told the Thunder Mountain Republican Women, praising a strict new statute designed to curb illegal immigration. In a closely watched campaign increasingly defined by who can take the harder line, Hayworth is a border hawk who called his book about immigration policy "Whatever It Takes."

But McCain, seeking his fifth term, is not about to be out-toughed this year. Once seen as more moderate on immigration, McCain has also endorsed the state law, which requires police to question people they "reasonably suspect" are here illegally. And he wants to send thousands of National Guard soldiers to the border.