Even in a Congress packed with safe incumbents, Sen. Chuck Grassley (R-Iowa) stands out for his Olympian political standing in his home state.

First elected to the Senate in 1980, Grassley has won at least 65 percent of the vote in each of his four re-election campaigns. In fact, Grassley’s 70 percent vote share in 2004 was the highest ever in a contested Senate race in Iowa, breaking the record set a dozen years earlier.

Grassley is strongly favored to win a sixth term next year, though Democratic officials promise they will give him a tough race after years of watching him win overwhelmingly against middling competition. Party strategists suggest that Grassley is not as invincible as is indicated by his past races, and they’re trying to cast him as a “career politician— who is obstructing a health care overhaul and other priorities of the Obama administration and Democratic-run Congress.

Democratic figures in Iowa and Washington, D.C., are promoting the candidacy of Roxanne Conlin, a wealthy trial lawyer, former federal prosecutor and unsuccessful gubernatorial candidate in 1982, who announced her campaign last month. She faces two lesser-known Democrats in the June primary.

Conlin is running a campaign that is focused on an opposition to “special interests,— such as large financial institutions that she says have left average Iowans behind.

“Iowans deserve better,— said Mark Daley, Conlin’s campaign manager. “After three decades in Washington, Chuck Grassley has lost touch with us.—

But it won’t be easy for Democrats to unseat Grassley. Though Iowa has trended Democratic in recent elections and on the voter registration rolls, the party is trying to supplant Grassley in a midterm election year that should be more friendly to Republicans. The left-leaning Democratic base that propelled Barack Obama to victory in the 2008 Iowa caucuses and subsequent general election is not as enthusiastic about voting in 2010 as the Republican base.

“This, I think, is going to be an awfully good Republican year, and I’m not sure the Democrats have got a very viable candidate to run against him,— David Yepsen, a former political columnist for the Des Moines Register, said of Grassley.

Even in his mid-70s, Grassley still has a reputation for keeping a vigorous work and campaign schedule. He visits all 99 counties every year, and his staff is said to be very responsive to constituent concerns.

Grassley’s conservative voting record might be a political liability if wasn’t leavened by an independent, rebellious streak. He’s attracted attention over the years for his high-profile opposition to wasteful spending at the Pentagon.

“He has a little bit of a maverick streak,— said Dennis Goldford, a political scientist at Drake University, and isn’t a “culture warrior— who focuses on hot-button social issues.

Though Grassley and liberal Sen. Tom Harkin (D-Iowa) often cancel each other out in their Senate votes, Hawkeye State voters have come to prefer a Grassley-Harkin bipartisan coexistence. Harkin heads the Health, Education, Labor and Pensions Committee and Grassley is the ranking member and former chairman of the Finance Committee.

Polls show Grassley with a big early lead over his Democratic challengers, with most Iowans approving of his service. An early November poll conducted by Selzer & Co. for the Des Moines Register pegged Grassley’s approval rating at 57 percent — much lower than his 75 percent rating in January, but higher than the ratings for either Harkin (54 percent) or Democratic Gov. Chet Culver (40 percent).

“Most politicians would die for a 57 percent job-approval rating,— Yepsen said.

Grassley’s approval rating took a dip as he assumed a higher profile against Democratic plans to overhaul health care. Democrats pointed to an August town hall meeting in Iowa at which Grassley, speaking in opposition to end-of-life counseling provisions in a health care plan, said there should not be “a government-run plan to decide when to pull the plug on grandma.—

“I think he’s a bit off his game,— said Bob Krause, a former state House Member and transportation official who is also seeking the Democratic nomination.

“In the past, he’s been able to think on his feet. I don’t think he does as much of that as he used to, and I think it’s become manifest with some of the gaffes that he’s had,—Krause said.

Grassley reported raising $865,000 in the third quarter and had $4.4 million in cash on hand as October began.

Conlin hasn’t yet filed a campaign report, though she has the personal resources and the ties to the well-heeled trial lawyer community that would enable her to wage a decently funded campaign.

Conlin “will have the resources she needs to compete,— Daley said. “At this point, she has not made a decision about any personal contributions to the campaign.—

Democratic leaders are promoting Conlin over Krause and Tom Fiegen, a lawyer and former state Senator. Neither Krause nor Fiegen has raised much money.

Krause, who’s running an all-volunteer campaign, said that Iowa Democratic voters are less swayed than voters in other states by campaign fundraising and endorsements. Iowa Democrats will give the Senate candidates a careful vetting, he said.

Iowa voters “tend to look at the person, they tend to research their decisions and vote on those without really being overwhelmed by the money,— said Krause, who has said he’ll release a “comprehensive jobs strategy— in about a week.

Though Fiegen and Krause have plenty of disagreements with Grassley — Fiegen criticized the Senator for a 2005 bankruptcy bill that he said favored the financial industry, and Krause criticized his record on veterans issues — they’ve also lodged criticisms at Conlin.

Fiegen said Republicans will exploit Conlin’s background as a trial lawyer. Fiegen, the Iowa Republican Party and the conservative political group American Future Fund accused Conlin and other lawyers of pocketing more money in attorney’s fees than they secured in funding for Iowa schools in a 2007 settlement of a class-action lawsuit against Microsoft.

“I’ve certainly had a lot of Iowans talking to me about her baggage, and the Republican Party is going to make it an issue,— Fiegen said. “And so as we go through the primary, I’m going to raise those issues with Iowa Democrats and see if they really want to have as their standard-bearer somebody that has that kind of baggage.—

Daley denounced the attack and said that Conlin “secured one of the largest investments in history for Iowa schools.—

“That such a false, negative smear campaign has already started is a testament to just how competitive this general election will be,— Daley said.

Republicans, meanwhile, are content to let the Democrats fight among themselves.

“As the Democrat candidates move leftward in their three-way primary fight, Sen. Grassley continues to represent Iowa with an independent voice in the United States Senate and has some of the highest approval numbers of any elected official in the state,— said Colin Reed, a spokesman for the National Republican Senatorial Committee. “While his general election opponent remains to be determined, Sen. Grassley is well-positioned heading into next year’s election.—