WASHINGTON — The U.S. Senate unanimously approved a resolution by voice vote on Thursday to bar its members from using prediction markets. The measure, written as a change to the Senate's rules, takes effect immediately.

Sen. Bernie Moreno, R-Ohio, sponsored the resolution. "United States senators have no business engaging in speculative activities like prediction markets while collecting a taxpayer-funded paycheck, period," Moreno said.

Sen. Alex Padilla, D-Calif., proposed an amendment to broaden the resolution to include Senate staff. Senate Minority Leader Chuck Schumer encouraged the House and the Trump administration to adopt the same restriction.

"We must never allow Congress to turn into a casino where members representing the public can gamble on wars or economic crises or elections," Schumer said. "That would destroy the very principle of representative government."

Sens. Todd Young, R-Ind., and Elissa Slotkin, D-Mich., introduced a bill to ban all federally elected officials and government employees from using insider information to make prediction market bets. Young said the resolution was a good first step and encouraged the Senate to take up their bill.

Lawmakers have voiced concerns that people might be making public wagers on the war with Iran. A U.S. special forces soldier was charged with using classified information to bet on the January capture of Venezuela's then-president, Nicolas Maduro.

Prediction market platforms including Polymarket and Kalshi have drawn attention as the business has expanded. Polymarket has been criticized as a venue for offshore trades that are beyond the reach of U.S. regulators. New accounts on the platform made highly specific, well-timed bets on whether the U.S. and Iran would reach a ceasefire on April 7, resulting in hundreds of thousands of dollars in profits for those accounts.

On the same day a report on the activity was published, the White House warned staff against using private information to trade on prediction markets. The administration has been a key ally of the growing prediction market industry in a legal fight with states seeking to ban the platforms. Donald Trump Jr., the president's eldest son, is an adviser for both Polymarket and Kalshi. Truth Social is launching a cryptocurrency-based prediction market called Truth Predict.