The Senate path for legislation to curb gun violence is about to hit a brick wall, any so-called evidence of progress notwithstanding.

Majority Leader Harry Reid, who’s spent his career cultivating support from the National Rifle Association, announced Wednesday morning that he would vote for both of the most ambitious gun control goals set by President Barack Obama — a ban on a long roster of military-style assault rifles and a prohibition on ammunition clips with more than 10 rounds.

Both proposals are still guaranteed to be rejected without any suspense later in the day. And so will the bipartisan compromise for expanding background checks on would-be gun buyers. Democratic Sen. Joe Manchin III of West Virginia, the amendment’s author along with Republican Sen. Patrick J. Toomey of Pennsylvania, conceded as much on Wednesday morning. “We will not get the votes today,” Manchin told NBC News, although soon afterward his office issued a statement insisting the senator had not given up.

Manchin and Toomey have 50 Democratic votes and five Republican votes locked up, meaning there’s a comfortable majority in the Senate for a proposal that continues to receive support from even broader majorities in most national polling. But, under an agreement designed to forestall weeks of filibusters from both the Senate’s gun rights and the gun control camps, all nine amendments being voted on starting at 4 p.m. will need 60 “yes” votes to succeed.

That supermajority requirement will probably result in no changes at all to the underlying bill. The assault weapons and high-capacity magazine bans will get fewer than 50 votes, even with Reid’s belated backing. The background check compromise will come up short.

And the six amendments designed to weaken the measure are all underdogs for adoption, although opponents of expanding gun rights are most worried about two of them: One would effectively eliminate any existing state restrictions on the carrying of concealed weapons. The other is a GOP substitute, unveiled Wednesday by Sens. Charles E Grassley and Ted Cruz, that would include a background check system endorsed by the NRA.

And if there’s a vote to pass the bill as it’s now written, the outcome is certain defeat. That’s because it would require background checks not only at gun shows and before online transactions, which are the focus of Manchin-Toomey language, but also before almost all non-commercial gun transactions. (The checks are now required only for customers at licensed gun dealers.)

The underlying bill does two other things Obama wants and most lawmakers support: It toughens the gun trafficking criminal statute and delivers federal aid for school security. But the current state of play suggests the president is about to come up totally empty-handed on an issue he’s devoted significant political capital to since the massacre of 20 first-graders and six educators at a suburban Connecticut elementary school. That was a month after winning re-election on a platform that totally ignored gun control.

“Every once and awhile we are confronted with an issue that should transcend politics,” he said in an interview that aired on NBC’s “Today.” “And now’s the time for us to take some measure of action that’s going to prevent some of these tragedies from happening again.”

The fate of his gun control push and his call for an immigration overhaul both rest with the diminishing ranks of centrists in each party. The whip counts on the background check compromise suggest that few of them are willing to go out on a limb on this week’s showdown votes, which could suggest that support for the immigration bill is quietly growing.

Besides Toomey, the four Republicans who have made clear they will vote for his amendment are Sens. Susan Collins of Maine, Mark S. Kirk of Illinois, John McCain of Arizona and Kelly Ayotte of New Hampshire. Efforts came up empty on Wednesday to negotiate minor changes in the background check system that would have eased the rules in rural areas and won over two more: Sens. Lisa Murkowski of Alaska and John Hoeven of North Dakota.

The Democrats least likely to vote for the amendment — especially once it becomes clear it lacks the votes with or without their support — are Sens. Mark Pryor of Arkansas, Mark Begich of Alaska, Max Baucus of Montana, Mary L. Landrieu of Louisiana and Heidi Heitkamp of North Dakota.