A federal judge in Massachusetts has stopped President Trump's plan to change US elections. The judge supported a group of Democratic state attorneys general who said the plan was against the Constitution. Trump's order, issued in March, wanted to make people show proof of citizenship to register to vote. It also wanted to only count mailed ballots that arrived by Election Day and link federal election money to states following this new deadline. The White House said the order would make sure elections were "free, fair, and honest." However, Judge Denise J. Casper decided that the states would probably win their legal case. She stated that the Constitution does not give the President specific powers over elections. The judge also blocked the part of the order that required states to reject any mail-in or absentee ballots received after Election Day. This is the second time Trump's election order has faced a legal problem, as a judge in Washington D.C. had already blocked parts of it.