Thursday is showdown day in the Senate over gun control legislation, with the Democratic leadership promising to move forward in a bid to overcome GOP objections.

"We are going to vote Thursday," Senate Majority Leader Harry Reid, D-Nev., said today. "It will be real slap in the face to American people not to do something on background checks, on school safety, on federal trafficking -everybody thinks it's a good idea."

Reid will file cloture on the bill tonight, setting up a Thursday showdown vote. The vote will not be on the overall legislation. It will be a procedural vote on the "motion to proceed" - aka, move to the bill. Republicans have threatened to filibuster the procedural vote, in essence standing in the way of the bill moving forward toward an up or down vote.

The bill needs 60 votes in order to override the Republican filibuster.

When asked if he has the votes he needs Reid answered, "I don't know."

If the bill gets 60 votes to proceed on Thursday that means that debate will start on the bill, with an amendment process, which will lead to a final vote on the overall legislation.

As ABC News' Jeff Zeleny reported this morning, Reid, Democrat of Nevada, has set a tentative deadline of later today for a compromise deal to be brokered on a key piece of the legislation on background checks.

Two senators - Joe Manchin, a West Virginia Democrat, and Pat Toomey, a Republican from Pennsylvania, are working on a possible bipartisan compromise on background checks. The plan would allow close friends and family to be excluded from those background checks if they are selling or trading guns to each other.

Reid said he told his fellow Democratic Senators today at their weekly caucus luncheon that he "admired" Senator Manchin for "stepping out and trying to do something constructive."

If the Senate moves toward the bill he said he would like a possible Manchin/Toomey proposal to be "one of the first" amendments offered.

Reid said the Senators do not have agreement yet but are anticipated to provide an update around 5 p.m.