US President Donald Trump’s presidential campaign has put out an explosive new ad calling Democrats “complicit” in murders committed by illegal immigrants, during the government shutdown triggered partly by an impasse over immigration.

The Trump campaign released the ad, titled “Complicit”, on the first anniversary of the president’s inauguration.

It focuses on undocumented immigrant, Luis Bracamontes, charged in the 2014 killings of two police officers in Sacramento, California. The man’s lawyers had questioned his sanity, but a judge found him mentally competent to stand trial, according to a report last week in the Sacramento Bee.

“Democrats who stand in our way will be complicit in every murder committed by illegal immigrants,” the ad says, as the President blames opposition Democrats for the shutdown crippling the government and the nation.

The new ad is likely to anger Democrats and immigration advocates and could inflame tensions over the issue on Capitol Hill, where Democrats and Republicans worked through the weekend to reach an agreement that would reopen the government.

A news release announcing the ad blamed Senate Democratic Leader Chuck Schumer for the shutdown, accusing him and Democrats of “holding lawful citizens hostage over their demands for amnesty for illegal immigrants”.

“This is a shameless attempt by the President to distract from the Trump shutdown,” Senator Schumer’s spokesman said in an email.

“Rather than campaigning, he should do his job and negotiate a deal to … address the needs of the American people.”

Mr Trump filed for re-election the day he took office, an unusual move that has allowed him to begin campaigning long before the November 2020 election.

Trump calls for ‘nuclear option’

Meanwhile, Mr Trump said on Sunday afternoon (US time) that Republicans should change the Senate rules to fund the government, if the government shutdown stalemate continued.

The current rules require a super-majority for appropriations bills to pass.

“The Dems (Democrats) just want illegal immigrants to pour into our nation unchecked. If stalemate continues, Republicans should go to 51 per cent (Nuclear Option) and vote on real, long term budget,” Mr Trump tweeted on Sunday.

Great to see how hard Republicans are fighting for our Military and Safety at the Border. The Dems just want illegal immigrants to pour into our nation unchecked. If stalemate continues, Republicans should go to 51% (Nuclear Option) and vote on real, long term budget, no C.R.’s!

— Donald J. Trump (@realDonaldTrump) January 21, 2018

But the radical proposal was almost immediately rejected by Republican and Senate Leader Mitch McConnell.

Senate Republicans oppose changing the Senate rules so that legislation to fund the government and end the current shutdown could pass with a simple majority, the spokesman said.

“The Republican Conference opposes changing the rules on legislation,” the spokesman said in an email.

Current Senate rules require a super-majority of three-fifths of the chamber, usually 60 out of 100, for legislation to clear procedural hurdles and pass.

Funding for federal agencies ran out on Saturday with Trump and Republican lawmakers locked in a stand-off with Democrats. There appeared to be no clear path for a quick end to the crisis.

Democrats say short-term spending legislation must include protections for illegal immigrants brought to the US as children, known as “Dreamers”. Republicans, who have a slim 51-49 Senate majority, said they would not negotiate on immigration until the government was reopened.

Democrat brands Trump ‘draft dodger’

Army veteran and Democrat senator Tammy Duckworth hit out at Mr Trump’s weekend tweet that Democrats were “holding our military hostage over their desire to have unchecked illegal immigration.”

Senator Duckworth, who lost both legs while serving slammed Mr Trump in the Senate on Saturday, calling him a “five-deferment draft dodger”.

“Does he even know that there are service members who are in harm’s way right now, watching him, looking for their commander in chief to show leadership, rather than to try to deflect blame?” Senator Duckworth asked.

“I spent my entire adult life looking out for the well-being, the training, the equipping of the troops for whom I was responsible,” she continued.

“Sadly, this is something the current occupant of the Oval Office does not seem to care to do, and I will not be lectured about what our military needs by a five-deferment draft dodger.”

– with AAP