Matched against Christie Vilsack, wife of former Iowa Go.v Tom Vilsack who is now Secretary of Agriculture, Grassley leads 51 percent to 40 percent with 9 percent undecided. Vilsack said she is considering the race.

Grassley leads bankruptcy attorney and former state legislator Tom Feigen by 54 percent to 31 percent with 15 percent undecided. Feigen has strongly signalled his intention to run.

Grassley leads former state legislator Bob Krause, who has announced his candidacy, by 52 percent to 35 percent with 13 percent undecided.

Grassley leads civil rights attorney Roxanne Conlin, who ran unsuccesfully for governor in 1982, by 51 percent to 39 percent with 10 percent undecided. Conlin says she's not running.

None of those margins over the Democrats match Grassley's re-election numbers. Since 1986, he has rolled up between 66 percent and 70 percent of the vote in four races.