White House officials are now openly conceding that President Obama's gun control package could die on Capitol Hill, a development analysts said would cast a pall over the president's second-term agenda and weaken his leverage with Republicans.

The president's trek to Denver on Wednesday was his latest attempt to regain momentum on the issue of gun violence, on which Obama has so far failed to close a deal despite a substantial investment of political capital.

"There doesn't have to be a conflict between protecting our citizens and protecting our Second Amendment rights," Obama said, surrounded by law enforcement officers in the Colorado capital.

But an overwhelming number of Republicans and a handful of red-state Democrats aren't buying that message.

Unlike immigration, which the White House views as a political winner even if the GOP kills reforms, new gun restrictions don't enjoy the same level of support along party lines. Obama can't merely bank on painting Republicans as obstructionists for political gain, analysts said.

"I don't think Republicans would lose the House [in 2014] simply because they blocked the president's gun initiatives," said Nathan Gonzales, deputy editor of the nonpartisan Rothenberg Political Report.

And from a policy perspective, this may represent Obama's last, best shot to achieve the types of firearms laws long rebuffed by the powerful gun lobby in Washington.

"It has to be done this calendar year -- and that's being generous," Gonzales added.

It's been more than 100 days since the December massacre at Sandy Hook Elementary School in Newtown, Conn., the event that sparked the latest efforts to place new restrictions on guns, and administration officials worry that the longer it takes to pass something, the less likely the president will succeed.

"People here in Washington may be getting cold feet," Obama senior strategist Dan Pfeiffer said Wednesday morning during a breakfast organized by Politico. "I think on a whole host of issues Washington tends to be a lagging indicator on public opinion."

For weeks, Obama has been portraying his gun recommendations -- an assault weapons ban, a prohibition on high-capacity ammo magazines and universal background checks -- as widely supported by the American public. An inability to deliver such reforms would create doubts about the White House's political clout.

Ironically, Obama may not have the most to lose if he fails on Capitol Hill.

"It could be most damaging to the vice president and his 2016 hopes because he's been so out front on this issue," said Dotty Lynch, a communications professor at American University. "I think Obama would be hurt if it's perceived he didn't do all he could [to pass new gun restrictions]."

After putting Biden in charge of working with Republicans on budget issues, Obama again tapped the vice president to help on guns with the hope that the former Delaware senator could win over moderate Republicans to the president's cause.

That hasn't happened. And the White House could be left to pick up the pieces of another unsuccessful push for sweeping, national gun control measures.

"It'd be tough to spin," said one veteran Democratic strategist with close ties to the White House. "The president can batter Republicans all he wants -- and he should -- but the negatives of not delivering on guns would overshadow that message."