WASHINGTON — The U.S. Justice Department on Thursday formally expressed its support for a group of Asian Americans who are suing Harvard University, claiming that it discriminates against them in its admissions program.

Their lawsuit is the latest effort by opponents of affirmative action to scale back programs that consider an applicant's race as one factor in deciding who can attend the nation's colleges and universities. Efforts to get the Supreme Court to end affirmative action have been unsuccessful, though the court has imposed additional restrictions.

"No American should be denied admission to school because of their race," said Attorney General Jeff Sessions in announcing that the Justice Department filed a document known as a statement of interest, allowing the government to support one side in civil lawsuits between two private parties.

In explaining its decision to enter the case, the Justice Department said, "Asian Americans face a significant disadvantage in Harvard's admissions program compared to applicants of other races."

Harvard has failed to demonstrate that considerations of race as a last resort to achieve a goal of campus diversity and cannot explain how much weight it gives to an applicant's race, it said.

The government's statement of interest said Harvard aims for the same racial demographics in each entering class, in spite of the Supreme Court's ban on quotas and racial balancing. Asian Americans made up 18 percent of the admitted classes in 2014 and 2015 and 20 percent in 2016 and 2017.

Harvard has steadfastly denied that it violates the Supreme Court's affirmative action rulings.

"Harvard College does not discriminate against applicants from any group in its admission processes," the university said, adding that it will "vigorously defend the right of Harvard and other universities to seek the education benefits that come from a class that is diverse on multiple dimensions."

The lawsuit was filed in 2014 and has involved court fights over how much Harvard is obligated to reveal about the mechanics of its admissions practices. Though it is a private university, it receives millions in federal grants, requiring it to abide by federal civil rights laws that ban discrimination based on race and other factors.

"Harvard has long since abandoned an admissions policy that purported to merely use race contextually to fill the last few seats in the entering freshman class. Harvard now labels every applicant by race on the claim that it is pursuing the so-called 'critical mass' diversity objective," the lawsuit said.

The group suing Harvard, Students for Fair Admissions, is made up of Asian Americans and others who have been denied admission to Harvard, and is led by Edward Blum, a consistent opponent of affirmative action. His efforts were behind the Supreme Court's most recent affirmative action decisions involving the program at the University of Texas at Austin.

The group's website seeks to hear from students who did not get into the schools of their choice. "Were You Denied Admission to College? It may be because you're the wrong race," the site says.

The American Civil Liberties Union said Thursday morning it planned to file a friend-of-the-court brief in support of Harvard, citing the Trump administration's prior advocacy of 'race-blind' admissions policies.