Des Moines — Sen. Roger W. Jepsen, Republican and loyal Reagan supporter, thought about the entry of Iowa Congressman Tom Harkin, Democrat, into the race for his Senate seat and pronounced that he was pleased.
''The choice is very clear,'' he said last week as he traveled between events , including a radio talk show and speeches in Des Moines. With 10 months until the polls open, the Jepsen schedule already resembled an all-out campaign.
For more than a year Senator Jepsen has been near the top of the list of Republicans most likely to lose in 1984, largely because of his lackluster approval ratings among Iowans.
But just as Representative Harkin officially opens his campaign, the senator's prospects look brighter. The Iowa Poll, which once showed Jepsen trailing, recently showed him pulling even with his challenger. Many in Iowa are settling in for a long, hard race.
''I think it will be close until the end,'' predicts Iowa Gov. Terry E. Branstad, a Republican who in 1982 won his own come-from-behind election.
The campaign will offer voters, as Jepsen said, a clear-cut choice. It pits a Republican senator who stands on the far right of his party against an unabashed progressive Democrat.
Jepsen has been a back-bencher in his freshman term, although he recently became chairman, for one year, of the Joint Economic Committee, a panel that has more symbolic prestige than power.
Harkin, a 10-year US House veteran, has had a high profile on Capitol Hill. He has made both headlines and policy through his interest in farm legislation and human rights in Central America.
The senator is a strong abortion foe.
The congressman favors freedom of choice on abortion.
And so it goes, with the two candidates dividing on virtually every major issue of the day, from Lebanon to labor to oil company mergers.
Even as Harkin formally announced his campaign last week, the tone of the campaign was clear. Returning to his home town of Cumming, Harkin reminded well-wishers that ''we learned to care for one another.'' He called for caring for the poor and elderly instead of ''rewarding those in society who already have too much.''
Outside of the Roman Catholic parish hall where Harkin made his announcement, a small band of abortion foes carried signs of protest against him. The day before, a group from the far right of the Iowa GOP called a press conference to brand Harkin as a ''radical.''
Harkin professes to be unafraid of such attacks, noting that he has long represented the most conservative district in the state and yet has handily won reelection five times. ''This campaign is not going to be about liberal/conservative,'' he holds. ''It's going to be about leadership.''
Although few lawmakers look more senatorial than Jepsen, the ''quality'' of the handsome, white-haired senator is generally seen as his most vulnerable point. Iowans have not forgotten that their senator made headlines in Washington by driving alone in a commuter lane reserved for carpools. When stopped by police, he cited his constitutional right not to be arrested while en route to his duties in Congress.
Months hence, a caller to a Des Moines radio talk show last week ribbed the senator, asking him, ''You still driving in the fast lane, Roger?''
''Absolutely not,'' responded Jepsen. ''I corrected that one.''
Jepsen, who is a member of the Senate Armed Services Committee, has also been criticized for having a Marine lieutenant colonel working in his office full-time to assist Iowa manufacturers seeking military contracts.
Since Iowa ranks near the bottom in winning federal contracts, Jepsen makes no apologies. ''It's a nonpolitical thing, bringing jobs and business to Iowa, '' he said in an interview. ''There are several businesses that have gotten contracts.'' He said that his aides could provide a ''laundry list'' of those contracts.
Jepsen aides could provide only one example, however - a printing contract to a minority business estimated at $35,000. Press aide James Lafferty also cited a case of Jepsen helping to save defense-related jobs for Iowans working in a Moline, Ill., plant.
Despite his critics, both Republicans and Democrats observe that Jepsen should not be underestimated.
''In Jepsen's entire career, he's always found a way to land on his feet,'' says John C. Law, past executive director of the Iowa Democratic Committee.
A veteran of five state contests, Jepsen commented during a visit to the Iowa Capitol, ''I've never lost an election in the past, and I don't intend to lose this one.''
Moreover, some Iowans are defensive about outside criticism of their senator. ''It strikes me that Iowans react much like a family does,'' says a lobbyist in the State Capitol. ''You close ranks.''
The Republican senator has already scored some points by lambasting Harkin for his major role in passing a dairy support bill, while Iowa has few dairy farmers. And while Harkin tries to make leadership the issue, Jepsen will be pointing to the liberal Harkin voting record.
Jepsen's most potent ally may be the economy, however. Farmers in Iowa, helped by the federal payment-in-kind (PIK) program, are uncommonly optimistic.
At a farm trade fair in Des Moines last week, they talked of planting big crops, seed dealers said they were sold out, and machinery dealers spoke cheerfully of the best sales in years.
''The economic recovery is broad, deep, and sustainable,'' Jepsen repeated several times during his visits around Des Moines. The brighter economic picture could make voters more satisfied with its current officeholders, including Reagan and Jepsen.