Among the bills blocked were those that would require a ban on gun sales to people on the US terrorist watch list.
The US Senate has blocked a series of proposals aimed at strengthening gun control, including a bill that would have stopped the sale of guns to terrorists.
The Democratic Party had proposed a ban on gun sales to suspected terrorists but this fell 13 votes short of the 60 required.
A Republican Party proposal for a similar ban but only if prosecutors could convince a judge in three days that the would-be buyer was involved in terrorism was also defeated by the same margin.
A proposal by a Democratic senator to expand background checks and close the gun show loophole – currently no checks are required for people buying guns at gun shows – was brought down by 56-44.
A Republican counter-proposal to bolster background checks with more money for the FBI-operated checking system and the requirement for states to send more criminal records to the FBI was also defeated 53-47, along with its second part which would have revamped language forbidding some people with mental health issues from buying a gun.
The Democrats had said this would weaken protection.
The news comes eight days after Omar Mateen, who declared his allegiance to terrorist group Islamic State, walked into a gay nightclub and opened fire, killing 49 people and injuring 53.
Police said in the attack’s aftermath that Mateen had bought his weapons legally, despite his 10-month inclusion on a federal terrorism watch list.
Currently, people buying guns from federally-licensed dealers can be denied for several reasons, mainly due to serious crimes or mental health problems – but there’s no specific ban on selling guns to those on the terrorist watch list.
That list contains around 1 million people – among them fewer than 5,000 Americans or permanent residents of the US, according to government figures.
Democrats called the Republican proposals unacceptably weak, while Republicans described the Democratic plans as overly restrictive.
The results show the continuing power of the National Rifle Association in US politics – the group had urged its supporters to lobby senators to oppose the Democratic bills.
It also highlighted the pressure on each party to give little ground on the emotional issue going in to November’s presidential and congressional elections.
Senate Minority Leader Harry Reid, a Democrat from Nevada, said: “Republicans say, ‘Hey look, we tried’, and all the time, their cheerleaders, the bosses at the NRA, are cheering them.”
But Senate Majority Leader Mitch McConnell, Republican of Kentucky, said the Orlando shootings had proved that the best way to defeat extremists is to defeat groups such as IS overseas.
He added: “Look, no one wants terrorists to be able to buy guns or explosives,” suggesting that Democrats were using the votes “as an opportunity to push a partisan agenda or craft the next 30-second campaign ad,” while Republicans wanted “real solutions”.