Washington (CNN) Hillary Clinton is the first presidential candidate in a generation to make gun control a top-tier campaign issue. But even if she wins on November 8, the ability to implement much of her agenda will be extremely limited.

That's because Congress is reluctant to touch it.

Republicans are expected to retain control of the House and even if Democrats capture the Senate they will not be close to the 60 votes needed to break a filibuster. That's how the last serious gun control measure, the Manchin-Toomey bill to extend background checks, failed in 2013.

"The only way anything is ever going to happen on gun control is with the support of Republicans, especially in the House, and that is difficult to see happening any time soon," said Jim Manley, a former top aide to then-Senate Majority Leader Harry Reid who now works as director of the communications practice at QGA public affairs.

Reflecting these political realities on Capitol Hill, Clinton spokesman Brian Fallon and New York Sen. Chuck Schumer, who stands to become majority leader if Democrats win control of the upper chamber, are already signaling that the gun issue would take a backseat to immigration and infrastructure during her first 100 Days if Clinton is elected.

For the past two decades, Democrats have been cautious when approaching the gun issue, afraid to antagonize the powerful National Rifle Association and other Second Amendment groups. But a series of recent mass shootings and a changing electorate have started to change the politics of gun control for national Democrats.

"Americans are fed up with the pace of mass shootings and the deepening violence within our cities," Sen. Chris Murphy, D-Connecticut, told CNN. "I don't think any nation could live through massacres like Sandy Hook, Charleston, San Bernardino, and Orlando and not end up in a different place."

Starting on October 13 of last year when she sharply criticized Sen. Bernie Sanders at a CNN debate for voting against the Brady Bill and for voting to shield gun manufacturers from lawsuits, Clinton has made gun violence a key issue in her second White House bid.

"She didn't just talk about it in the primary -- just to create a point of differentiation with Bernie Sanders," said Murphy. "She talked about it in each of her three debates with Trump -- even when she wasn't asked about it."

Murphy, whose personal outrage at gun violence was heightened by the 2012 murder of 20 schoolchildren and six adult staff members at Sandy Hook Elementary School in his home state of Connecticut, is hoping that GOP lawmakers will go along with stricter gun control after studying the results of the election.

"This is the first election in which Republicans are paying a price for their position on guns," said Murphy who filibustered for more than 14 hours over the summer calling for more gun control. "Republicans are certainly being weighed down by Trump. But their internal polls are also being weighed down by their opposition to common sense measures like closing the terror gun loophole."

The NRA, which is spending $24 million on television ads to support Donald Trump, rejects the notion that Clinton is only after "common-sense regulations" like keeping people on terror watch lists from obtaining guns. The NRA says it supported legislation by Texas GOP Sen. John Cornyn that not only would have denied terrorists the ability to buy firearms but also would have provided due process protections for law abiding Americans who incorrectly ended up on the "secret government blacklist." The NRA maintains that if Democrats had truly been interested in solving this issue -- rather than having an issue to use in television ads -- they would have approved the Cornyn bill.

"This election is about the Supreme Court," said Jennifer Baker, the NRA's director of public affairs. "The 2008 Heller decision guarantees an individual's right to keep a gun in your home for self-protection," she added, referring to a landmark Supreme Court ruling.

"Clinton said at a closed-door 2015 fundraiser that the Court got it 'wrong' on Heller. Scalia was the deciding vote. Scalia is now gone. If you overturn Heller, it paves the way for extreme gun control like banning handguns," Baker said.

At the final presidential debate last week, Clinton was asked about her closed-door comments. She acknowledged that she disagreed with the legal reasoning in the Heller decision while re-affirming her support for the Second Amendment.

"I disagreed with the way the court applied the Second Amendment in that case," said Clinton. "Because what the District of Columbia was trying to do was to protect toddlers from guns."

Clinton was criticized following the debate by fact checkers for misleadingly suggesting that the law's focus was keeping toddlers away from guns when the thrust of the law struck down by the court was prohibiting the private ownership of handguns in the District of Columbia.

"Clinton in her own words thinks the Supreme Court 'got it wrong' in the Heller decision," said the NRA's Baker. "That means that she does not believe that Americans have a right to keep a gun in their home for their self-protection. She can't be trusted."

Murphy disagrees with the argument advanced by Trump and the NRA that a Clinton presidency would lead to overturning the Heller decision and open the door for states to ban handguns.

"I think her agenda is clear: expanded background checks and keeping guns from terrorists," said Murphy. "Even if she got half of that done, it would result in a dramatic reduction in gun deaths."