The South Dakota Senate race is suddenly tighter than expected, but national Republicans say they aren't ready to panic.

The contest to succeed retiring Democratic Sen. Tim Johnson could put a wrinkle in GOP prospects for winning six seats and Senate control on Nov. 4.

But Republicans monitoring the race told the Washington Examiner that they trust internal surveys being conducted by GOP pollster Glen Bolger. Bolger has a good track record in South Dakota and counts Sen. John Thune, R-S.D., as a client, including during his competitive Senate campaigns in 2002 and 2004.

Those internal polls, Republicans say, show their nominee, former Gov. Mike Rounds, with a low double-digit lead of 11 to 14 percentage points over independent Larry Pressler and Democrat Rick Weiland.

That’s in stark contrast to an auto-dial poll of 616 likely voters conducted Oct. 1 – 5 by Survey USA that showed Rounds leading Pressler 35 percent to 32 percent, with Weiland grabbing 28 percent and a second independent, Gordon Howie, at three percent. The margin of error was four percentage points.

Republicans concede that they are concerned with the recent trend and confirmed that party strategists are working on a strategy to shore up support for Rounds. Thune is expected to hit the campaign trail for Rounds between now and Election Day, a potentially important asset if the race stays close.

“South Dakota is becoming a bigger headache,” a Republican said. “I don't think it is in the slam dunk category anymore.”

Republicans blame Rounds’ trouble partly on his lackluster campaign. Specifically, they say he treated his Senate race like his easy campaigns for governor. Rounds, they say, failed to appreciate that while South Dakotans almost never elect Democrats to the statehouse, they are comfortable sending them to Washington, requiring Republicans to run more vigorously.

In particular, Rounds has been unwilling to run negative ads — as he has been in every race he’s ever run.

Meanwhile, his opponents have been attacking him for a federal immigration visa program that was bungled by the state agency charged with running it. Republicans say Rounds wasn't at fault, but the problems occurred during his gubernatorial administration.

Rounds is also suffering from South Dakota voters’ mistaken image of Pressler. He is a former Republican who served three terms in the Senate until he was ousted by Johnson in 1996. Pressler has since drifted to the left, openly supporting President Obama and his policies. But South Dakota insiders say Pressler has surged on the strength of support from older GOP voters who still think of him as a “good Republican.”

Insiders say there is a very simple solution and it’s a reason they remain encouraged that this problem will be mitigated: Run television ads that target Pressler for supporting Obama and administration policies. That could be more imperative now that the Democratic Senatorial Campaign Committee and other liberal groups have seized on the new polls and announced plans to attack Rounds. The DSCC said it would spend $1 million.

“Those points need to be made; they’re going to be made soon,” a South Dakota Republican told the Examiner.

There still the matter of who is going to do it, however.

National Republicans hope that the recent polling and fresh attacks from the Democrats will shake Rounds out of complacency and motivate him to embrace negative advertising for the first time.

The NRSC, the Senate GOP campaign arm, declined to detail its involvement in this race. The committee and other Republican groups have focused their resources on flipping competitive, Democratic-held seats and aren’t eager to invest in a race previously considered a sure thing.

At press time, the Rounds campaign had responded to a request for comment but had yet to answer questions posed by the Examiner.

“They’ve been in touch all along with the Rounds folks,” a GOP insider said of the NRSC. “The hope is that they don’t have to spend any money. But they would spend money if they need to.”