The Senate voted to open debate on gun control legislation Thursday:

Sixteen Republicans joined with 52 Democrats to approve a motion to proceed. Two Democrats joined with 29 Republicans to oppose the motion . . .

The measure up for consideration still contains largely Democratic proposals to expand background checks, make gun trafficking a federal crime and provide more federal dollars for school security programs. In the coming days, Reid has promised senators of both parties an opportunity to introduce amendments to strengthen, weaken or at least tweak the current language.

In 2010, a year-long investigation by The Post revealed a disturbing view of the illegal movement of guns throughout the country, a movement kept secret by federal privacy laws intended to protect gun owners. Watch the videos and read more about the black market for guns here.

Many criminals get their guns from friends or on the street, Brad Plumer wrote Thursday at Wonkblog:

Sen. Joe Manchin III (D-W.Va.), along side Sen. Patrick J. Toomey (R-Penn.), unveiled a bipartisan deal to expand background checks to all commercial sales of guns on Wednesday. (The Washington Post)

The new compromise bill put forward by Sens. Joe Manchin III (D-W.Va.) and Patrick J. Toomey (R-Pa.) would require background checks for anyone who buys a firearm at a gun show or on the Internet. That would make it marginally harder for people who are prohibited from owning guns to acquire them. But it would still leave the vast majority of private transfers untouched — including the most common ways for criminals to get guns.

“So it is a step forward, but a small step,” says Philip Cook, a criminologist at Duke University.

That small step has depended heavily on Manchin, who has become an unlikely advocate for stronger gun control:

For Manchin, that agreement was the payoff from months of relationship-building with Republicans, including nights of pizza and beer on a senator-stuffed boat called the Black Tie. The final deal was worked out over the past week, and concluded late Tuesday with a huddle at a rooftop birthday party for TV host Joe Scarborough.

There, Sen. Charles E. Schumer (D-N.Y.) agreed to support the proposal — but to skip the news conference so his enemies would not become the bill’s enemies.

The big news instead was delivered by Manchin, in his third year in the Senate, serving notice that Washington had underestimated his ambition and his flexibility. (Read the complete profile here, and read an interview with Manchin here.)

Discuss this topic and other political issues in the politics discussion forums.