The Richmond, Calif. city council on Tuesday unanimously passed a resolution in support of a congressional investigation into whether President Donald Trump's business holdings warrant impeachment.

"This is our voice. This is our country. We have a right to speak up," said Councilmember Gayle McLaughlin, who introduced the resolution.

It says that Trump is in violation of the Foreign and Domestic Emoluments Clause of the U.S. Constitution, and calls upon the House of Representatives to direct its Judiciary Committee to investigate.

That "previously little-known constitutional provision," the Mercury News wrote, "says that U.S. presidents may not accept gifts or make a profit from any foreign state. The clause has never been tested in court. But activists say the president's many business holdings continue to benefit him directly, even as he has handed over the day-to-day operations of his businesses to his children."

While Richmond may be first city to issue the call, it's far from the only voice in the chorus.

Watchdog group Citizens for Responsibility and Ethics in Washington filed a federal lawsuit last month arguing that Trump was in violation of the Foreign Emoluments Clause, and New York Rep. Jerrold Nadler this month filed a "resolution of inquiry" that, according to author and RootsAction.org co-founder Norman Solomon, "amounts to the first legislative step toward impeachment."

A Public Policy Polling (PPP) survey released this month also found Trump's approval rating plummeting, with support for his impeachment at 46 percent—up from 35 percent two weeks earlier—and, as of this writing, over 887,184 people have signed a petition calling for his impeachment.