President Obama is launching a series of ads aimed at women voters in key swing states, hoping to widen the gender gap in his campaign against former Massachusetts governor Mitt Romney.

The campaign starts with “First Law,” touting Obama’s decision to sign the Lily Ledbetter Fair Pay Act on his first day in office. The law made it easier to sue employers over pay discrimination by extending the statute of limitations.

“The son of a single mom. Proud father of two daughters,” a female narrator says over shots of Obama as a child and with his own children. “President Obama knows that women being paid 77 cents on the dollar for doing the same work as men isn’t just unfair, it hurts families.”

The massive 19-point advantage Obama held with women a few months ago has not lasted, as Republican women coalesced around Romney. A May Washington Post-ABC News poll gave the president only a seven-point lead with female voters. (Surveys have shown Obama with a bigger edge in swing states). In 2008, Obama won women by 13 points; he will need a sizable gender gap to win again.

“First Law” will air in Colorado, Florida, Iowa, North Carolina, Nevada, Ohio and Virginia.