WASHINGTON (Reuters) - The U.S. Congress, facing a Friday deadline for approving about $450 billion in funding for several government agencies or forcing them into a partial shutdown, is steering toward a two-week extension as President Donald Trump and Democrats argue over border wall funding.

FILE PHOTO: People walk by the U.S. Capitol building in Washington, U.S., February 8, 2018. REUTERS/ Leah Millis

The Republican-led House of Representatives will seek later this week to pass an extension to Dec. 21, congressional aides said.

The Senate, narrowly controlled by Republicans, would also have to approve the measure this week, which would continue funding for several agencies at last year’s levels.

Without action by Congress, federal agencies including the Department of Agriculture, State Department and Department of Homeland Security would find themselves without any money to pay employees and administer programs through the fiscal year that ends next Sept. 30.

Trump has demanded $5 billion for this year as part of his plan to build a wall on the border with Mexico that Democrats argue would be ineffective at keeping out illegal immigrants and illicit drugs.

Instead, Democrats want to continue improving less costly fencing and employing high-tech instruments to detect illegal border crossings.

The total cost of the wall project is expected to exceed $25 billion and could spark lawsuits over the government seizing private property in some construction areas.

In a Monday Twitter post, Trump wrote: “We would save Billions of Dollars if the Democrats would give us the votes to build the Wall. Either way, people will NOT be allowed into our Country illegally! We will close the entire Southern Border if necessary. Also, STOP THE DRUGS!”

Previously, Trump threatened to force a partial government shutdown if Congress did not give him the money he wants for the wall.

The president had been scheduled to meet on Tuesday with House Democratic leader Nancy Pelosi and Senate Democratic leader Chuck Schumer to discuss the impasse.

But memorial observances in the Capitol for former President George H.W. Bush have postponed that meeting. Democrats will take control of the House in January following last month’s congressional elections.

If at any point Congress and Trump cannot agree on legislation to keep the government agencies running, essential services, such as the FBI and other federal law enforcement, would continue.

But some vital programs would have to be suspended until the money dispute was resolved.

For example, visitors most likely would not be admitted to national parks, some Securities and Exchange Commission and Internal Revenue Service activities could be curtailed, as well as some Justice Department programs.

Special Counsel Robert Mueller’s investigation of Russia’s meddling in the 2016 U.S. presidential election would continue, according to congressional aides.

Funding already is in place for many agencies, such as the Defense Department.