A swath of the San Gabriel Mountains near Los Angeles will be declared a national monument by President Barack Obama, a California congresswoman said on Wednesday, capping an 11-year effort that became mired in partisan politics.

The move comes at the request of Democratic Representative Judy Chu, whose legislation to protect the area is stuck in Congress along with other wilderness bills as Republicans and Democrats feud.

Chu said the White House confirmed Obama's support and that the designation would be made on Friday.

"With this designation, the San Gabriels will become a priority, opening up new streams of funding that can be used to ensure that the mountains achieve their full potential for all the people who have gone there to hike, fish, or just enjoy fresh air,” said Chu, whose district includes part of the area.

The 540-square mile section of the Angeles National Forest to be protected under the order attracts 3 million visitors a year, but graffiti mars the landscape, and the U.S. Forest Service has little money for signage or even restroom repair, Chu said.

Legislation to protect the mountains has been introduced twice in Congress, once in 2003, leading to a 10-year-study by the U.S. Park Service, and then in June 2014, when Chu submitted a bill to designate them a national recreation area.

After her bill became stuck in a subcommittee, Chu asked Obama to use his executive authority to declare part of the area a national monument.

That angered some local officials and many Republicans, who said it was an end-run around Congress.

Judy Nelson, mayor of the foothill city of Glendora, said naming the area a national monument instead of a national recreation area could invoke different environmental protection rules and might harm businesses.

About 150 people protested the designation outside Chu's Pasadena office on Monday.

Obama's declaration will affect only land already designated as a national forest, and will not include San Bernardino County, whose governing body voted to oppose the action.

“The San Gabriel Mountains are a dramatic landmark that can be seen from the desert to the sea,” said Daniel Rossman, chairman of a coalition of groups that pressed for the designation. “And when it becomes a national monument, the forest will receive the recognition and attention it so rightfully deserves.”