A federal judge in Massachusetts has stopped President Donald Trump's plan to change U.S. elections. The judge agreed with a group of Democratic state attorneys general who said the plan was against the Constitution. Trump's order, given in March, wanted people to show proof of citizenship to register to vote. It also wanted to only count mailed ballots that arrived by Election Day and to give federal money for elections only if states followed the new rules. The White House said the order would make sure elections were "free, fair, and honest." But Judge Denise J. Casper decided that the states would probably win their legal cases. She said the Constitution does not give the President special powers over elections. The ruling also stopped a part of the order that told states to not count any mail-in or absentee ballots that arrived 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 stopped parts of it.