JANESVILLE, Wis. — Mitt Romney’s No. 2 has a safety net in case the GOP presidential ticket doesn’t win the White House.

Vice presidential candidate Paul Ryan also is on the ballot seeking another term as a Wisconsin congressman.

Filming for Ryan’s re-election commercials finished a few days before Romney introduced the Wisconsin congressman as his running mate, and the ads will air this fall as planned.

Wisconsin law allows Ryan to seek both offices at once. He usually wins by comfortable margins, but his district tilts Democratic in presidential races and, this year, Ryan won’t have the luxury of much time back home.

“I’m already on the ballot. You can’t even go off the ballot,” he told CBS’ “60 Minutes.”

Wisconsin’s 1st Congressional District stretches from the shores of Lake Michigan through industrial zones, bedroom communities and farm fields until it reaches Ryan’s hometown of Janesville to the west. Republicans have filled the seat since 1995, with Ryan serving the area for all but four of those years. But Democrats — and even a Progressive Party member — have held it over the years, including former Clinton administration Defense Secretary Les Aspin.

Democrats would need to convert more than two dozen seats to retake the majority in Congress. So far there’s little indication they will put extra effort into toppling Ryan, the House Budget chairman. Throughout his career, Ryan has far outperformed the top of his party’s ticket, including in 2008, when President Barack Obama narrowly won a district where Ryan racked up 64 percent of the vote.

Ryan’s opponent back home is Rob Zerban, a former Kenosha County board member and catering company owner. At last report, Ryan’s $5.4 million campaign stockpile was 10 times bigger than what Zerban had at his disposal.

But Zerban argues that he can benefit from the heightened scrutiny Ryan will be under as a national candidate.

“He’s now on a national stage. This budget is going to receive such scrutiny that people as they find out more and more about it, they’re going to reject it wholeheartedly,” Zerban said.

Retired purchasing manager Jon Flora, 68, of Janesville, said it doesn’t bother him if Ryan puts less energy into running for Congress. His wife, Vicki, a retired banker, chimed in that she doubts it will matter anyway.

“He’s untouchable,” she said. “You’ve got to like him even if you don’t want to.”

Airline pilot John Catlin, 48, lamented that Ryan running for vice president would rob the district of a powerful voice in Congress. He said a double run could leave people confused.

“A lot of people will be wondering which office he’s really trying to get,” Catlin said. “Do you vote for him twice?”