A bipartisan group of senators has struck a deal to expand gun background checks to all commercial sales – whether at gun shows, via the Internet, or in any circumstance involving paid advertising, the Washington Post reports. The proposed agreement would be more stringent than current law, which requires checks when purchases are made through a licensed dealer, but less strict than sought by President Obama and congressional Democrats, who were seeking to expand background checks to nearly every kind of sale. The agreement should secure enough bipartisan support to allow the Senate debate on bill that would expand background checks, make gun trafficking a federal crime for the first time, and bolster federal funding for school security plans. Senate Democratic leaders have said they will permit senators of both parties to introduce amendments to the measure. The deal on background checks was struck by Sens. Joe Manchin D-W Va.), Charles Schumer (D-N.Y.), Mark Kirk (R-Il.) and Patrick Toomey (R-Pa.) The Senate has scheduled a vote tomorrow to start the debate, launching the most wide-ranging and ambitious battle over gun control on Capitol Hill in 20 years.