A final vote is expected tomorrow in the U.S. Senate on a campaign finance reform measure. Iowa Senator Tom Harkin says the bill isn’t perfect, but it’s a good first step toward restoring integrity to the electoral process.Harkin is offering an amendment to the bill that would let candidates make agreements for voluntary spending limits in various races.In U.S. Senate general election races, spending would be limited to one-million dollars, plus 50-cents for every person of voting age in the state, ranging from 1.2 million in Wyoming to 12-million in California.Harkin says his amendment would also enforce the spending limits. If a candidate exceeds the limit by more than ten thousand dollars, his opponent would get twice the amount by which the other candidate went over.