To mitigate the impact of Libertarian candidates in North Carolina and other states, Republicans are enlisting Senator Rand Paul of Kentucky to appeal to Libertarian-leaning voters. The U.S. Chamber of Commerce last week recorded commercials featuring Mr. Paul, which will air in closely contested states…

In North Carolina, for example, Sean Haugh, the Libertarian nominee for the Senate, who works as a pizza delivery man, has been drawing 6 percent in recent polls. That could be enough to hurt the chances of Thom Tillis, the Republican who is challenging the Democratic incumbent, Kay Hagan. Despite President Obama’s declining popularity in the state, Ms. Hagan has retained a narrow lead over Mr. Tillis…

“At the end of the primary, you have that transition period,” said Mr. Tillis, the State House speaker, predicting that Mr. Haugh would draw 4 percent to 5 percent of the vote “at the very most.” But Republicans recognize that Mr. Haugh’s candidacy could siphon votes from the right. In addition to the ad he recorded in support of Mr. Tillis, Mr. Paul will campaign with him this week in Raleigh.

“He can send a signal to that community that you don’t want to waste your vote,” Rob Collins, the executive director of the National Republican Senatorial Committee, said of Mr. Paul.