President Barack Obama plans to use the power of his office to push for stricter gun-control measures as part of a broad-based approach aimed at averting mass shootings like the one that occurred Friday in Connecticut, White House Press Secretary Jay Carney said Monday.

Mr. Carney declined to detail a timeline or lay out any policy proposals, but emphasized that this effort would begin within weeks as the president suggested Sunday during a prayer service in Newtown, Conn.

"He...