Topeka ? U.S. Sen. Pat Roberts, R-Kan., has taken a 57 percent to 30 percent lead over Democrat Jim Slattery, according to the latest Rasmussen Reports poll.

Last month, a Rasmussen survey showed Roberts’ support dropped below 50 percent, and he led Slattery 48 percent to 39 percent. But the July poll showed Roberts gaining a double-digit lead.

The Roberts’ camp touted the newer poll.

“We don’t run our campaign by polls. However, we have always believed this would be the result when Kansans are faced with the choice of Sen. Pat Roberts, who never stops working for Kansas, and Jim Slattery, a lobbyist who quit working for Kansas years ago to enrich himself off special interests,” said Roberts’ spokeswoman Molly Haase.

But Slattery’s campaign said Roberts’ rise in the polls was the result of a wave of negative ads.

“Roberts has spent hundreds of thousands of dollars running negative ads personally attacking Jim,” said Slattery spokeswoman Abbie Hodgson. “Therefore, we’re not surprised that there has been some movement in his numbers.

“However, we’re confident that once Kansans learn about Roberts’ abysmal record on energy policy, the economy, health care and the war that they will vote for change in November.”

Slattery faces an underdog candidate in Lee Jones in the Aug. 5 Democratic Party primary.

Roberts was first elected to the Senate in 1996 after serving 16 years in the House. Slattery served as a U.S. House member from Topeka from 1983 through 1995. He ran for governor and lost in 1994 and then worked as a lobbyist in Washington, D.C.

The July poll was based on a survey of 500 likely voters and has a margin of error of plus or minus 4.5 percentage points.