Maryland Attorney General Brian E. Frosh announced Friday plans to use his newfound power to sue the federal government by joining a Washington state lawsuit trying to upend Republican President Donald Trump’s new travel ban.

The General Assembly granted Frosh, a Democrat, sweeping authority last month to file lawsuits against the Trump administration without first securing Republican Gov. Larry Hogan’s approval.

When Frosh joins Washington’s lawsuit on Monday, he will use that power for the first time.

Maryland, along with New York, Oregon, Massachusetts and Minnesota, will join the suit, which contends that both of Trump’s temporary travel bans for people from certain predominantly Muslim countries are unconstitutional.

The president unveiled a more narrow executive order this week to replace the more expansive one, which was temporarily blocked by a court after Washington state’s initial lawsuit.

“The more voices, the better,” Frosh said in an interview. “It’s a Muslim ban. It’s illegal, it’s unconstitutional. It’s un-American.”

The Trump administration has said the travel restrictions are designed to bolster national security. The executive orders have come under scrutiny as a potentially unconstitutional religious test because the president campaigned on barring Muslims from entering the country.

The new, narrower order — it bans travel from six countries instead of seven and scales back other provisions — was designed to withstand legal challenges.

White House spokesman Sean Spicer said this week the administration felt “very confident with how that was crafted and the input that was given.”

Washington’s Democratic Attorney General Bob Ferguson announced Thursday that he planned to challenge the constitutionality of the more narrow ban. Hawaii’s attorney general, Democrat Doug Chin, was the first to announce a legal challenge to it.

Frosh said Maryland’s involvement would be handled by an assistant attorney general and the legal work would be spread out among the states involved.

Frosh unilaterally joining the suit is a departure from how Maryland has handled litigation in the more than 150 years since it re-established the office of attorney general in 1864. Until General Assembly Democrats pushed through a measure last month to let him bypass the governor, all such lawsuits required approval of the governor.

Maryland was one of nine states that did not grant autonomy to the attorney general through common law.

The legislature is also considering providing the attorney general’s office an extra $1 million a year and five more attorneys, beginning in 2018, to assist with federal litigation.

When he made the requests a month ago, Frosh said he had no immediate plans to sue the Trump administration. But his appearance at a standing-room-only town hall meeting in Columbia this week foreshadowed his decision to join the Washington state lawsuit.

Frosh told those assembled at the Owen Brown Interfaith Center that Trump’s travel order was “inhumane.”

Ali Manzoor, a Muslim law clerk for a Baltimore circuit judge who attended the meeting, said the Trump administration’s order violated “everything that the United States stood for.”

Two people — including Paul Brockman, a Howard County resident — protested outside.

“Frosh needs to be deported,” Brockman said.

Though he can now act on his own authority, Frosh is required to give the governor a 10-day notification in advance of a lawsuit, whenever possible. Frosh said he notified Hogan, but received no response.

A spokeswoman for the governor declined to comment on the merits of the legal action, but explained why Hogan did not offer the attorney general his opinion.

“We didn't respond because the legislature in their infinite wisdom saw fit to remove the governor’s historical authority over this process,” spokeswoman Amelia Chasse said in an email.

“The fact that they are still trying to compel the governor to respond to something he no longer has any authority over shows their action was more about politics than substance.”

Baltimore Sun Media Group reporter Fatimah Waseem and the Associated Press contributed to this article.

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