Donald Trump will on Monday will ask Congress for an additional $8.6bn to pay for the wall he has promised to build on the border with Mexico, officials familiar with his 2020 budget request said.

Asked if that meant there would be another budget fight over the wall, like that which led to a long and damaging government shutdown at the turn of the year, White House economic adviser Larry Kudlow said: “I suppose there will be ...

“He’s going to stay with his wall and he’s going to stay with the border security theme. I think it’s essential.”

Budgets are mainly seen as blueprints for White House priorities, often panned on Capitol Hill, where lawmakers craft the bills that fund the government if the president signs them.

Speaking to Fox News Sunday, Kudlow also said the Trump 2020 budget would contain a 5% across-the-board reduction in domestic spending, and would “point a steady glide path” towards lower federal spending and borrowing.

There was “no reason to obsess” about the budget deficit, he said, as long as it remains below 5% of the overall economy. The deficit is approaching $1n. Kudlow also said he was confident economic growth would top 3% in 2019 and beyond. Other observers have predicted lower growth.

The demand for wall funding is more than six times what Congress allocated for such projects in each of the past two fiscal years, and 6% more than Trump has corralled by invoking controversial emergency powers.

We have provided the course of action, the strategy and the request to finish the job Anonymous White House official

Democrats, who oppose the wall as unnecessary and immoral, control the House of Representatives. Republicans control the Senate.

Trump built his 2016 campaign around his promise of a wall, which he said Mexico would pay for. It will not. A bruising battle with Congress over wall funding resulted in a five-week partial federal government shutdown that ended in January. Trump’s budget could touch off a sequel, ahead of three fiscal deadlines this fall.

Funding legislation needs to be passed before 1 October or the government could shut down again. If Congress and the White House fail to agree to lift mandatory spending caps set in a 2011 law, steep automatic cuts to many programs will kick in. Around the same time, Trump and lawmakers must agree to lift the debt ceiling or risk a default.

Regardless of whether Congress passes it, the Trump budget request will help the president frame his argument on border security as the 2020 election takes shape.

“It gives the president the ability to say he has fulfilled his commitment to gain operational control of the south-west border,” an administration official, speaking to Reuters on condition of anonymity, said of the budget request.

“We have provided the course of action, the strategy and the request to finish the job. It’s a question of will Congress allow us to finish the job,” a second official said.

Trump’s request is based on a 2017 plan put forward by Customs and Border Protection (CBP) officials to build or replace 722 miles of barrier along the border, which in total is estimated to cost about $18bn. Only 111 miles have been built.

Following the rejection of his last wall funding demand, Trump declared a national emergency and redirected $601m in treasury forfeiture funds, $2.5bn in defense department drug interdiction funds and $3.6bn from a military construction budget.

The $8.6bn in proposed wall funding for fiscal 2020 would include $5bn from the Department of Homeland Security and $3.6bn from military construction. The budget proposal will also include another $3.6m to make up for any military construction projects delayed by the wall, officials said.

Trump will propose an overall 5% increase to the Department of Homeland Security budget, including $3.3bn, or 22% more, for CBP, and $1.2bn more for Immigration and Customs Enforcement, a 16% hike, officials said. The budget proposal includes a plan to hire more than 2,800 law enforcement and support personnel for the agencies, and 100 immigration judge teams, officials said.

Many lawmakers accused Trump of overstepping his constitutional powers. The House has voted to revoke the emergency and the Senate is likely to do the same this week. Trump is expected to veto the resolution.

A coalition of state governments led by California has sued Trump to block the emergency move, though legal experts have said the lawsuits face a difficult road.