It's a make-or-break week in the U.S. Senate for a gun control bill Democrats are trying to push through before the national revulsion over the Sandy Hook Elementary School massacre fades.

As families of gun violence victims, including the parents of 20 schoolchildren killed in the December shooting in Newtown, Conn., lobby Congress for the stricter gun legislation, Senate Republicans are threatening to filibuster the measure.

The Senate votes Thursday to move forward with the legislation, so debate can begin on the gun control bill. Democrats will need 60 votes to overcome a filibuster. Although they're confident, Democrats are in a tight spot because the party has members in red states up for re-election in 2014.

A bipartisan deal to extend background checks to online sales and gun shows raised the hopes that the bill will pass.

“There are powerful feelings about each of these proposals -- both strong support and strong opposition,” Senate Majority Leader Harry Reid, D-Nev., said.

“But whichever side you are on, we ought to be able to agree to engage in a thoughtful debate about these measures. We ought to be able to agree to a careful examination of the culture of violence that has grown in this nation. ... I have promised as open an amendment process as possible on this bill. As always, the ease of that process will depend upon the good will of all senators.”

So what does Republican support for a vote on gun control look like right now? Here's a link showing how the Democratic Policy and Communications Center sums it up. It shows that 12 senators, including Arizona's John McCain and South Carolina's Lindsey Graham were pro-vote; 14 senators -- Florida's Marco Rubio and Kentucky's Rand Paul -- were not in favor of a vote; and it was uncertain how the others would vote.