The National Rifle Association's Political Victory Fund also said it plans a major ad campaign for Roberts. The group said it would use television ads and direct mail.
Roberts, 78, who is seeking a fourth term in what has become one of the most reliably Republican states in the country, is facing an unexpectedly tight race against independent Greg Orman. The Democratic candidate, Shawnee County District Attorney Chad Taylor, dropped out of the race after polls showed Kansas voters are unhappy with Roberts but that he and Orman were splitting the opposition vote.
Both Palin and the NRA attempted to link Orman to President Obama.
"The NRA is committed to ensuring that Kansas voters know Pat Roberts is the only candidate in this race who will protect their Second Amendment rights and that a vote for Greg Orman is a vote for Obama's extreme gun control agenda." NRA-PVF Chairman Chris W. Cox said in a statement.
Palin campaigned with Roberts in Independence, a small city near the Oklahoma line. She said Roberts stood with Sen. Ted Cruz, R-Texas, last year when he filibustered Obamacare.
Orman's independence is a fraud, Palin said.
"I know independence," Palin said. "Supporting Barack Obama, supporting Obamacare, supporting amnesty, supporting Harry Reid? That's not independent. That's someone who's trying to snooker ya, Kansas."
Palin came to Kansas a day after Sen. John McCain, R-Ariz., the man who made her a national figure during the 2008 presidential race. Earlier in the week, former Vice President Bob Dole, who also represented Kansas in the Senate, campaigned with Roberts, criticizing Cruz at one event.
Roberts came close to defeat in the Republican primary. He has had to deal with stories that he does not really live in the state, renting a room from a supporter while his real home is in Virginia.