Three of the potential presidential candidates for 2008 — four if you count Iowa Governor Tom Vilsack — are in Iowa this weekend to campaign on behalf of Iowa candidates on the ballot this November.

Senator John Kerry of Massachusetts, the 2004 Democratic presidential nominee, started his Iowa trip Friday by testifying at a Senate field hearing in Iowa City focused on cancer research. Kerry, a prostate cancer survivor, wears one of those yellow “livestrong” wrist bands popularized by cycling legend Lance Armstrong. “I was in Sioux City at a rally on the river and at the end of the rally when I had talked about stem cell research and how we needed to be the country that needs to find the cures and moves forward, I went down into the crowd and this woman, in tears, who had been fighting cancer thrust this yellow wristband into my hand and said ‘You have to wear this,'” Kerry says. “I put it on right then and there in Iowa and…I’ve never taken it off since.”

Kerry says he’s had to change the band a few times, but wears a yellow band every day as a reminder of his successful battle with cancer and the unsuccessful cancer fights he’s witnessed. “I lost my dad to prostate cancer and I lost my ex-wife three months ago, at age 61, to cancer and I lost my granddad to colon cancer,” Kerry says. “So we’ve had cancer in the family.”

On Friday, Kerry got on a bicycle and rode part of the RAGBRAI route. Next Saturday, Kerry will get on a bicycle and ride 110-miles in Massachusetts in the PanMass Challenge, which Kerry says is the single-largest “bike-a-thon” cancer fundraiser in America. This year’s fundraising goal, for example, is 24-million dollars.

Armstrong testified at the hearing with Kerry, and both decried federal budget cutbacks in funding for the National Cancer Institute. “Here we are on the threshhold of breaking through…We’ve made so many advances it’s indefensible for mere millions (for cancer research) to be fought over when billions are going to Iraq and elsewhere, not to mention oil companies and wealthy people,” Kerry says.

Senator Bill Frist of Tennessee, the Republican leader of the U.S. Senate, is also in Iowa this weekend. Frist, who is a medical doctor, too, says federal funding for cancer research at the National Institutes for Health has doubled in the eight years he’s been in the senate. “It’s a huge committment that has been fulfilled and now we’re seeing the great advances that have resulted from that,” Frist says. “I strongly encourage continued investment.” Frist says it’ll be three or four months before final numbers are known on cancer funding for the next federal fiscal year.

This weekend Frist will literally run in Iowa — in the BIX road race in Davenport. Governor Vilsack’s also scheduled to run in the race.

Frist will also campaign with Republican gubernatorial candidate Jim Nussle, G-O-P congressional candidate Mike Whalen and statehouse candidates. Frist says Republicans up and down the ticket have a “unified” theme. Frist says he’ll talk about Republican accomplishments, like tax cuts, and job creation. Frist says he’ll look to the future as well, and talk about tightening up the border, making the tax cuts permanent and “securing” America’s values. “I believe that for Republicans to win that we need to show the stark contrast between a country — at whatever level — a community, a country led by Democrats versus by Republicans,” Frist says.

Massachusetts Governor Mitt Romney will headline a Republican Party of Iowa fundraiser in Cedar Rapids this (Saturday) night. Governor Tom Vilsack will be in Johnston, Iowa, this (Saturday) morning to help a legislative candidate raise money.