And the reason he gives is a reflection of President Obama wanting to do too much ,too quickly, and without a thought to the political consequences for members of congress.
The bipartisan effort to expand background checks will not have the votes to advance in the Senate today, according to one of the architects of the deal.
"We will not get the votes today," Sen. Joe Manchin, D-W.Va., told NBC News.
Potential supporters, Republican Sens. Jeff Flake, of Arizona, and Florida's Marco Rubio, could not risk a stand on background checks in the face of opposition from their conservative base because they are already leading on immigration, Manchin said.
Sources also told NBC News that the effort's proponents are 4 to 5 votes short, a gulf that could widen if Democrats in conservative states decide not to support the measure.
As the showdown vote draws near later Wednesday, an Associated Press-GfK poll shows ebbing public support for tightening gun control laws.
In the run-up to the roll call, so many Republicans had declared their opposition to the background check measure that supporters -- mostly Democrats -- had already seemed headed to defeat unless they could turn votes around in the final hours. Supporters seemed likely to lose some moderate Democratic senators as well.
"It's a struggle," New York Sen. Chuck Schumer, the No. 3 Senate Democrat, conceded on Tuesday.
Perhaps helping explain Democrats' problems, an AP-GfK poll this month showed that 49 percent of Americans support stricter gun laws. That was down from 58 percent who said so in January -- a month after the December killings of 20 children and six aides at a Newtown, Conn., elementary school propelled gun violence into a national issue.
Just over half the public -- 52 percent -- expressed disapproval in the new survey of how President Barack Obama has handled gun laws. Weeks after the Newtown slayings, Obama made a call for near universal background checks the heart of his gun control plan.
In the heat of emotion after Newtown, many Americans felt that Congress should "do something" about guns and gun violence. But once the outline of what Congress proposed to do became evident, support for gun control plummeted.
And note that in a couple of weeks, the Senate will address the immigration issue. It is a good metaphor for the Obama presidency; legislative overreach. Obama was able to pass Obamacare and the Dodd-Frank because of overwhelming Democratic representation in Congress. But this second term is turning into an unmitigated disaster as the president tried to force two major, contentious issues through the Democratic Senate, thus exposiing his friends (and opponents) to political pressures that will likely doom any kind of gun control and make immigration reform harder than it already was going to be.
Eight votes on gun control amendments are scheduled today. Will any of them pass? It doesn't look like they will, which means the overall bill is in serious jeapordy.