WASHINGTON (AFP) - President Barack Obama is poised to unveil a raft of executive actions to tackle US gun violence, kicking-off his last year in the White House with a show of political power.

Frustrated at the unbending political opposition to gun control, despite the American scourge of mass shootings, Obama is now looking to bypass Congress with executive steps that aides say will focus on regulating gun sales and curbing illegal purchases.

The proposals - being presented to Obama by Attorney General Loretta Lynch at the White House on Monday (Jan 4) - could tighten rules on gun dealers and crack down on "straw purchases" in which potentially suspect individuals buy guns through an intermediary.

White House spokesman Josh Earnest said Obama would make an announcement "quite soon" on steps the administration has concluded would help "keep guns out of the hands that people who shouldn't have them."

The measures are unlikely to address the more than 300 million guns already thought to be in circulation in the United States.

That, critics argue, means the steps will do little to stop gun violence that claims more than 30,000 lives in the country each year.

During Obama's seven years as president, mass shootings have killed Connecticut schoolchildren, South Carolina church goers, Colorado movie watchers and scores of others.

Polls had long shown most Americans support tougher gun laws, but that support has ebbed recently amid concerns about the Islamic State group and the wider threat from terrorism.

That could put pressure on Obama's Democratic allies who face tough election battles this Autumn.

On Thursday Obama will take part in a primetime town-hall style debate on gun control to try to boost his case.

The event, broadcast by CNN, will take place at George Mason University in Fairfax, in northern Virginia.

In a New Year's address to the nation, Obama voiced his determination to tackle what he called the "unfinished business" of curbing gun violence.

But Obama's decision to bypass Congressional opposition spells a political and legal fight for the coming election year.

The Republican-controlled Congress has already rejected measures to curb the sale of military-style semi-automatic rifles.

The leader of the House of Representatives, Paul Ryan on Monday accused Obama of "dismissiveness" toward Americans who value the constitutional right to bear arms.

"We all are pained by the recent atrocities in our country, but no change the president is reportedly considering would have prevented them," said Ryan.

"We have seen consistently that an underlying cause of these attacks has been mental illness."

"No president should be able to reverse legislative failure by executive fiat, not even incrementally," Ryan warned. "This is a dangerous level of executive overreach, and the country will not stand for it."

By using the last resort of executive action, Obama invites legal challenge alongside the predictable political opprobrium.

His lawyers have spent months "scrubbing" existing laws to see where rules could be tightened and loopholes closed, while surviving inevitable court challenges.

"A lot of the work that has gone on behind the scenes to take a look at what the president can do using his executive authority has been grounded in the knowledge that the gun lobby and the Republicans in Congress who regularly do their bidding are going to look for ways to try to stop it," said Earnest.

Similar executive efforts by Obama to bring millions of illegal immigrants out of the shadows by shielding them from deportation, have prompted a slew of lawsuits and left a key Obama policy goal in the hands of the Supreme Court.