Not including guns when talking about mass killings is "like not including cigarettes when discussing lung cancer," Sen. Charles E. Schumer (D-N.Y.) said as he began a round of questions.

Schumer is expected to emerge as the lead sponsor of legislation that would mandate background checks on most, if not all, gun buyers. He's been speaking with moderate senators, including Joe Manchin III (D-W. Va.), Mark Kirk (R-Ill.) and Tom Coburn (R-Okla.), about co-sponsoring the bill.

Schumer asked Baltimore City Police Chief James Johnson about the proposal and the chief endorsed the idea.

"It’s not an inconvenience," Johnson said of background checks on all gun buyers. "I can't write a ticket, a citation in a minute and a half. Even with technology I can’t do that. It's not inconvenient and it's fair to the gun owner and shop owner, too."

Johnson also noted that 74 percent of National Rifle Association members support broader background checks. H was referring to a recent poll by the Johns Hopkins Bloomberg School of Public Health -- an institute that benefits from financial donations from New York Mayor Michael Bloomberg, a leading gun control advocate.

Ed O’Keefe is covering the 2016 presidential campaign. He's covered presidential and congressional politics, Congress and federal agencies and spent a brief time covering the Iraq war.