Almost 200 Democratic lawmakers are suing Donald Trump over foreign money flowing into his global business empire.

The senators and representatives are plaintiffs in a lawsuit alleging Trump is violating the emoluments clause of the constitution. It is being filed early on Wednesday in the US district court for the District of Columbia, the lawmakers said.

The plaintiffs argue they have standing to sue because the clause says only Congress may approve foreign gifts and payments.

“The framers gave Congress a unique role, a unique right and responsibility,” said Senator Richard Blumenthal, a Connecticut Democrat who helped organize the lawsuit.

Although Trump turned over control of his real estate development, management and marketing company to his adult sons and a senior executive, he did not divest from it. That means he stands to benefit financially from the Trump Organization’s profits, including from foreign governments.

Since he has become president, the Trump Organization has secured dozens of potentially valuable patents, including in China, and collected fees from lobbyists working for Saudi Arabia and other countries using his properties.

The new suit – the third of its kind – says the full scope of foreign payments to the Trump Organization cannot be known because the president has not made public his tax returns.

Earlier this week, two Democratic attorneys general filed a similar claim. Days after Trump’s inauguration in January, a liberal-funded government watchdog filed an emoluments lawsuit. A restaurant group and two individuals in the hotel industry later joined as co-plaintiffs.

Trump and the Justice Department have called these lawsuits baseless. They argue the clause is not intended to prevent normal business such as hotel payments and real estate transactions.

John Conyers, a Michigan Democrat representative, said he and Blumenthal had amassed the “greatest number of congressional plaintiffs on any lawsuit against a president”. He said they were taking the action “not out of any sense of pleasure or partisanship but because President Trump has left us with no other option”.

Before the filing, only Democrats were asked to sign on, but Blumenthal and Conyers plan to send letters to their Republican colleagues on Wednesday asking them to join the effort.