CHICAGO, United States (AFP) — Former US president George W Bush on Monday called immigration a “blessing and a strength,” as lawmakers tussled with Donald Trump over border wall funding.

The Republican, who has largely stayed out of the spotlight after leaving office in 2009, did not explicitly criticize Trump or the border wall policy.

Speaking at a naturalisation ceremony for 51 new American citizens at the George W Bush Presidential Center in Dallas, Texas, the nation’s 43rd president called for reform of “outdated and ineffective” immigration laws. 

He also emphasised: “Borders are not arbitrary and they need to be respected.”

“Amid all the complications of policy, may we never forget that immigration is a blessing and a strength,” Bush said in prepared remarks. 

“I hope those responsible in Washington can dial down the rhetoric, put politics aside and modernise our immigration laws soon.”

Bush’s remarks came as Congress and the White House were gearing up for a court fight over Trump’s declarations of an emergency to fund construction of a border wall at the US-Mexico border.

Congress had refused to appropriate money for the project — a central promise of the Republican’s 2016 election campaign.

In an embarrassing rebuke to Trump, some fellow Republicans joined Democrats in voting to terminate his declaration of an emergency. Trump vetoed the legislation Friday.

Opponents, who accuse Trump of executive overreach and hyping the problem on the border, could now fight the emergency measure in court.