President Donald Trump speaks while participating in a tour of border wall prototypes. Kevin Lamarque | Reuters

President Donald Trump on Monday will ask the U.S. Congress for an additional $8.6 billion to help pay for the wall he promised to build on the southern border with Mexico to combat illegal immigration and drug trafficking, officials familiar with his 2020 budget request told Reuters. The demand is more than six times what Congress allocated for border projects in each of the past two fiscal years, and 6 percent more than Trump has corralled by invoking emergency powers this year. Democrats, who oppose the wall as unnecessary and immoral, control the U.S. House of Representatives, making it unlikely the Republican president's request will win congressional passage. Republicans control the Senate. The proposal comes on the heels of a bruising battle with Congress over wall funding that resulted in a five-week partial federal government shutdown that ended in January, and could touch off a sequel just ahead of a trifecta of ominous fiscal deadlines looming this fall. Regardless of whether Congress passes it, the budget request could help Trump frame his argument on border security as the 2020 presidential race begins to take shape, with the president seeking re-election. "Build the wall" was one of his signature campaign pledges in his first run for office in 2016. "Finish the wall" is already a feature of his re-election campaign, a rallying cry plastered across banners and signs at his campaign rallies.

Border Patrol agent Vincent Pirro walks towards prototypes for a border wall Tuesday, Feb. 5, 2019, in San Diego. Gregory Bull | AP

"It gives the president the ability to say he has fulfilled his commitment to gain operational control of the southwest border," an administration official, speaking 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 administration official said. Funding legislation needs to be passed before Oct. 1 - the start of the 2020 federal fiscal year - 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 in many programs would kick in. Around the same time, Trump and lawmakers must agree to lift the debt ceiling, or risk a default, which would have chaotic economic fallout.

722 miles of wall

Trump's wall request is based off a 2017 plan put forward by Customs and Border Protection officials to build or replace 722 miles of barrier along the border, which in total is estimated to cost about $18 billion. So far, only 111 miles have been built or are underway, officials said. In fiscal 2017, $341 million in funding was allocated for 40 miles of wall, and in 2018, another $1.375 billion was directed to 82 miles. For fiscal 2019, Trump demanded $5.7 billion in wall funds, but Congress appropriated only $1.375 billion for border fencing projects. Following the rejection of his wall funding demand, Trump declared the border was a national emergency - a move opposed by Democrats and some Republicans - and redirected $601 million in Treasury Department forfeiture funds, $2.5 billion in Defense Department drug interdiction funds and $3.6 billion from a military construction budget, for total spending of $8.1 billion for the wall. The administration has not estimated how far the 2019 funds will go, but officials said average costs are about $25 million per mile. Trump's $8.6 billion in proposed wall funding for fiscal 2020 would include $5 billion from the Department of Homeland Security budget and $3.6 billion from the Pentagon's military construction budget. The budget proposal will also include another $3.6 million in military construction funding to make up for any projects delayed by the wall, officials said.

Lt. Gen. Jeffrey Buchanan, U.S. Army North Commanding General discusses work completed on the Arizona-Mexico border wall Nov. 18, 2018 U.S. Army photo