Senate Democrats on Thursday blocked Sen. Rand Paul Randal (Rand) Howard PaulSecond GOP senator to quarantine after exposure to coronavirus GOP senator to quarantine after coronavirus exposure The Hill's Morning Report - Sponsored by National Industries for the Blind - Trump seeks to flip 'Rage' narrative; Dems block COVID-19 bill MORE's (R-Ky.) effort to tie a measure rolling back Washington, D.C.'s gun control laws to an ObamaCare repeal bill.

Senators voted 54-45 in favor of Paul's amendment, six votes short of 60 needed for approval.

Sens.(R-Texas),(R-S.C.) and(R-Fla.), who are running against Paul for their party's presidential nomination, supported the amendment. Sen.(R-Ill.) voted against the amendment, while Democratic Sen.(Ind.) voted for it.

Paul's proposal — which comes a day after a mass shooting in California resulting in the deaths of 14 people — would require the Government of the District of Columbia to grant concealed carry permits to both District residents and nonresidents. It would also require the District to honor concealed carry licenses from other states.

"Last week, the District of Columbia police chief said that if you see an active shooter, take them down," Paul said ahead of the vote. "The problem is it's very difficult to own a gun in D.C., and it's merely impossible to be able to have a gun with you if you were to see an active shooter."

The amendment would also allow for guns to be carried in public "non-sensitive" areas of federal property and eliminate current D.C. laws that restrict gun or ammunition ownership.

After the vote, Paul slammed his colleagues for blocking the proposal, saying that it underscores why "most of America rightfully believes that politicians in Washington are out of touch."

"Instead of standing up for the Second Amendment, some of my colleagues chose to keep in place restrictive gun control laws," he added in a statement. "I will keep fighting to bring much needed change to our legislative priorities and continue my effort to defeat the Washington machine."

Del. Eleanor Holmes Norton (D-D.C.) blasted the Kentucky Republican's proposal, saying Paul "has sacrificed his federalism principles and the democratic rights of 650,000 D.C. residents for political and personal gain."

Sen. Barbara Boxer Barbara Levy BoxerThe Hill's Morning Report - Presented by Facebook - Biden, Harris launch Trump offensive in first joint appearance Bottom line Polls show big bounce to Biden ahead of Super Tuesday MORE (D-Calif.) said she was "shocked" that Paul would offer the amendment.

"D.C. has its own unique needs. We know how many diplomats come here. We know the rest. It's quite different," she added. "We are a definite target, but the fact is I urge my colleagues to stand up and be counted here. On behalf of local control, I started off as a county supervisor. I didn't want other entities telling me what to do."

Democrats have pressured Republicans to take up and pass new gun control legislation in the wake of a stream of mass shootings in the United States.

Senators rejected tying all three amendments to the ObamaCare repeal bill.

The Senate will vote on the overall legislation later on Thursday evening. If it is approved and goes to the White House, President Obama is expected to veto it.

- Updated at 7:59 p.m.