US President Barack Obama quoted Jesus in his emotional speech announcing moves to tighten gun controls – but his transparent sincerity was not enough to shield him from a vicious Republican backlash.

In his address yesterday he wiped away tears as he recalled the Sandy Hook primary school shooting in December 2012 in which 20 children and six adults were killed.

"Every time I think about those kids, it gets me mad," Obama said, tears rolling down his cheek.

"That changed me, that day," he said, after being introduced by Mark Barden, whose seven-year-old son was killed in the shooting. "My hope earnestly has been that it would change the country."

He also referred to the death of Zaevion Dobson, a 15-year-old who was killed in Tennessee in December while protecting three girls from gunfire: "He gave his life to save theirs, an act of heroism a lot bigger than anything we should ever expect from a 15-year-old. 'Greater love hath no man than this, that a man lay down his life for his friends.'"

Obama said in his speech: "Each time this comes up we are fed the excuse that common-sense reforms like background checks might not have stopped the last massacre, or the one before that, or the one before that, so why bother trying. I reject that thinking. We know we can't stop every act of violence, every act of evil in the world. But maybe we could try to stop one act of evil, one act of violence."

However, despite America's shockingly high levels of gun violence and repeated mass shootings, his Republican opponents, backed by the powerful National Rifle Association (NRA), remain resolutely opposed to any attempt to curb gun ownership.

NRA lobbyist Chris Cox dismissed Obama's speech, saying: "The American people do not need more emotional, condescending lectures that are completely devoid of facts."

House of Representatives Speaker Paul Ryan said Obama's executive orders, "undermined liberty" and would be challenged in court.

Republican presidential frontrunner Donald Trump said that, if elected, he would reverse the measures.

The most robust response came from another leading contender for the Republican nomination, evangelical Ted Cruz, who placed an image on his donations website showing a Photoshopped Obama wearing combat gear with the caption: "Obama wants your guns. Support the protection of your Second Amendment rights!"

Other candidates also rushed to condemn Obama's move. Marco Rubio tweeted a link to an appearance on Fox News in which he described Obama's moves as "just one more way to make it harder for law-abiding people to buy weapons or to be able to protect their families. It's going to do nothing to prevent violence or crimes."

Ben Carson issued a series of tweets criticising Obama: "The President's actions have everything to do with advancing his political agenda & little to do with actually protecting American citizens," read one.

Among the measures proposed are background checks for all gun sellers, with an an expansion of the FBI's workforce to carry them out; States providing information on people disqualified from buying guns due to mental illness or domestic violence, and a request to Congress for $500m (£339m) to improve access to mental healthcare in the US. As Congress is Republican-controlled this is unlikely to be granted.

Obama's signal of tighter controls has also led to an increase in gun sales. According to Reuters, the stocks of gunmakers Smith & Wesson Holding Corp and Sturm Ruger & Co Inc have climbed since the announcement. On Tuesday, Smith & Wesson ended up 11.1 per cent to $25.86 a share and Sturm Ruger closed up 6.8 per cent at $65.54.