Biden: Background checks may come down to 'one or two senators'

But the vice president, speaking at the dedication of the University of Baltimore's new law center, predicted the administration would "prevail" on passing the legislation, championed by Sens. Joe Manchin (D-W.Va.) and Pat Toomey (R-Pa.).

"Whether it's tomorrow, or next month or next year, we are eventually going to reflect the view of the American public in the laws that we pass," Biden said.

Senate Majority Leader Harry Reid (D-Nev.) has indicated that the upper chamber will vote Wednesday on the Manchin-Toomey gun control compromise deal. Democratic aides say they have not yet cleared the 60-vote threshold necessary to avoid a filibuster, but hope that political pressure will sway some of the remaining undecided senators.

Earlier in the day, Biden attended the dedication ceremony of a Capitol meeting room named in honor of Gabe Zimmerman, an aide to former Rep. Gabrielle Giffords (D-Ariz.), who died in the 2011 Tucson shooting spree.

In Baltimore, Biden said Congress could learn from Maryland, whose General Assembly has approved tough new restrictions on gun ownership. On Wednesday, Biden will participate in a Google Hangout with mayors from across the country — including Baltimore Mayor Stephanie Rawlings-Blake — as he makes a last-ditch push to rally support for the gun legislation.

The vice president also pledged that the administration was providing "every resource available" to help investigators looking into Monday's bombing at the Boston Marathon.

"We will respond to these cowardly acts, we will find the perpetrators and bring them to justice," Biden said. "That I guarantee."

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