NEW YORK (AP) — New Republican-leaning groups are entering the presidential advertising fray as polling suggests Mitt Romney's campaign may be losing ground against President Barack Obama in key swing states.

The commercials, aimed at voters who supported Obama in 2008 but are undecided now, join those from the campaigns and outside groups swamping a narrow and possibly shrinking map of competitive states in the fast-moving presidential contest.

The ads also focus on female voters, a bloc where Romney badly lags Obama.

The group Americans for Job Security launched an ad in six swing states as part of an $8.7 million ad buy disclosed last week. Separately, a new conservative group bankrolled by billionaire Joe Ricketts, the Ending Spending Action Fund, is set to debut a $10 million, four-state ad campaign on Thursday.