Presaging a month-long air campaign, the House’s two national party committees are set to launch new independent expenditure ads in South Dakota today as they jockey for the high ground in the June 1 special election.

The ads are remarkably similar and detail the candidates’ plans for health care with a special focus on prescription drugs. Neither makes any mention of the opposition.

This buy marks the Democratic Congressional Campaign Committee’s first ad on behalf of attorney Stephanie Herseth (D).

The National Republican Congressional Committee has run two previous ads in the contest, both of which detail state Sen. Larry Diedrich’s (R) accomplishments in the state Legislature.

Each of the new ads are 30-second commercials and will run statewide.

The decision by both parties to wade into the campaign with positive commercials symbolizes the importance of the race nationally. Each party is seeking to seize — or at least lay claim to — the momentum heading into November, and the spots also highlight the reluctance on both sides to appear to be running a negative campaign.

“We felt at this point in the campaign that it would be beneficial for the NRCC to be back on TV,” explained Communications Director Carl Forti.

The party committee ads come just days after the first real scuffle between Diedrich and Herseth in the contest to replace former Rep. Bill Janklow (R), who resigned his seat Jan. 20.

The disagreement broke out late Friday when Diedrich put up an ad questioning Herseth’s support for making President Bush’s tax cuts permanent — the first commercial of the campaign in which a distinction was drawn between the candidates.

Herseth responded immediately with an ad of her own that said Diedrich was attempting to “mislead” voters about her tax stance.

“I’m committed to running a truthful campaign,” said Herseth in the spot. “It’s clear that Larry Diedrich is not.”

Both sides agree that South Dakota voters are uniquely conscious of the specter of negative campaigning, following the brutal gubernatorial and Senate campaigns they witnessed last cycle.

Even so, neither committee would rule out the possibility of running comparative or even negative commercials.

Forti said there is “no hesitancy on our part” to run hard-hitting ads if NRCC officials deem it necessary. He quickly added, however, that no final decision has been made concerning the content of the ads the committee will run.

Bernards refused to comment on the DCCC’s willingness or lack thereof to run ads drawing contrasts between the two candidates.

The Herseth campaign alleged late Monday that Republicans conducted focus groups as recently as two weeks ago that tested negative commercials for use against her.

The four potential ads tested included mentions of the fact that Herseth traveled to New York City to raise money for the race; that she advertised on a Democratic Web blog; an attempt to tie her to New York Sen. Hillary Clinton (D) and California Sen. Dianne Feinstein (D); and a final ad making clear that she favors abortion rights, according to Herseth spokesman Russ Levsen.

Levsen said Herseth learned of the focus groups through one of the participants.

Despite the explosive behind-the-scenes allegations, neither national party committee took any major risks in the new ads.

The DCCC ad features a variety of people testifying to the fact that “big insurance companies just have too much power over our health care.”

Herseth, they argue, will “stand up to corporate special interests” and “fix the Medicare prescription drug benefit.”

The NRCC ad is strikingly similar.

It begins with a narrator noting that many South Dakotans “can’t afford their prescriptions because drug companies put profits ahead of helping people.”

The ad goes on to detail Diedrich’s work in the state Senate to “pass Governor [Mike] Rounds’ [R] plan to join with other states to negotiate lower drug prices.”

The tagline of the DCCC ad is that Herseth “will stand up for us.”

Diedrich, by contrast, is “an experienced leader we can trust.”