Democrats offered their first show of unified opposition to President Trump on Tuesday, as elected officials across the country vowed to fight against a White House-ordered pause in grants, loans and other federal financial assistance.

Since Mr. Trump won the election in November, Democrats have debated how stridently to oppose the president and his administration. Some argued for the kind of wholesale defiance that characterized their response during Mr. Trump’s first term. Others, including those from places where Mr. Trump gained support in 2024, pushed to find areas of cooperation on issues like immigration and inflation.

But on Tuesday, the earliest sketches of a new playbook emerged, as Democrats across the ideological spectrum accused Mr. Trump of preying on the nation’s most vulnerable citizens by denying government aid for struggling families and the elderly and defunding police departments, transportation systems and hospitals.

“Donald Trump’s administration is lying to you,” Gov. JB Pritzker of Illinois said at a news conference Tuesday afternoon in Chicago. “What the president is trying to do is illegal.”

Democratic governors, attorneys general and mayors raised alarms about halting funding to programs that would be harmed, including child-care centers and food assistance, and pointed angrily to the sudden failure of the online portal through which state Medicaid departments receive federal funding.

“I will not stand by while the president attempts to disrupt vital programs that feed our kids, provide medical care to our families and support housing and education in our communities,” said Rob Bonta, the California attorney general, who helped organize a lawsuit to block the order that was quickly joined by two dozen Democratic attorneys general.

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