Former President Barack Obama has kept a relatively low profile since leaving office.
But that ended Thursday after Senate Republicans unveiled their health care bill.
In a lengthy Facebook post, Obama said there is a "fundamental meanness at the core" of both the Senate's and House's health care legislation.
He called the Senate's bill "not a health care bill" but a "massive transfer of wealth from middle-class and poor families to the richest people in America."
The bill would make significant changes to the Affordable Care Act, which Obama signed into law over seven years ago. Some Republican senators say the bill doesn't go far enough and are calling for a complete repeal.
The House's version of the bill, which passed that chamber in May, is a repeal and replacement of the Affordable Care Act.
Obama does have a stake in this. The Affordable Care Act is viewed as one of — if not the — signature achievement of his administration.
He wrote, "It remains my fervent hope that we step back and try to deliver on what the American people need."
At that point, he told his Facebook fans "it's possible" if they speak up. He said that the debate is "about the character of our country – who we are, and who we aspire to be. And that's always worth fighting for."