By Courtney Sherwood

PORTLAND, Ore. (Reuters) - Opening arguments in the trial of four men who took part in an armed occupation of a U.S. wildlife refuge last year are scheduled to begin on Tuesday in Oregon, after a jury previously acquitted seven other occupiers in a stinging defeat for prosecutors.

Duane Ehmer of Oregon, Jake Ryan of Montana, Darryl Thorn of Washington state and Jason Patrick of Georgia all face multiple charges of trespassing, conspiracy to impede federal employees through intimidation and tampering with vehicles and equipment.

They each face a variety of other criminal counts in the federal trial in Portland, Oregon.

Patrick, Ryan and Thorn were charged with possessing a firearm in a federal facility; Ehmer and Ryan face charges of degradation of government property for allegedly digging trenches at the wildlife center; and Patrick and Ehmer are charged with destroying or removing property items.

Authorities have called the 41-day occupation of the Malheur National Wildlife Refuge, which occurred in early 2016 in rural eastern Oregon, a lawless scheme to seize federal property by force. The trial represents an opportunity for U.S. prosecutors to potentially conclude the criminal case with a victory.

It would be a reversal from their loss last October, when a jury acquitted anti-government activist Ammon Bundy and six followers of conspiracy. It was the same charge brought against all four men in the latest group of defendants to face trial.

Bundy and his supporters cast the armed occupation of the federal wildlife refuge as a patriotic act of civil disobedience and have expressed opposition to U.S. government control over millions of acres of public lands in the West.

Ehmer, Ryan, Thorn and Patrick have pleaded not guilty in their case. The conspiracy charge brought against all four men carries a maximum sentence of six years in prison.

Last week, a jury of seven women and five men was seated for the trial, which is expected to last four weeks.

Fourteen other participants in the occupation pleaded guilty to various charges.

Ammon Bundy, his brother Ryan and their father Cliven Bundy are held in federal custody ahead of a trial scheduled to begin later this year in connection with another armed standoff with federal officers in 2014 in Nevada.