For environmental activists like Jessica Miller, 31, the passage of a major climate bill by the House last month should have been cause for euphoria. Instead she felt cheated.

Ms. Miller, an activist with Greenpeace, had worked hard on her own time to elect Barack Obama because he directly and urgently addressed the issue nearest her heart: climate change.

But over the last few months, as the ambitious climate legislation was watered down in the House without criticism from the president, Ms. Miller became disillusioned. She worried that the bill had been rendered meaningless  or had even undermined some goals Greenpeace had fought for. And she felt that the man she had thought of as her champion seemed oddly prone to compromise.

“I voted for the president, I canvassed for him, but we just haven’t seen leadership from him,” said Ms. Miller, who rappelled down Mount Rushmore on Wednesday with colleagues to unfurl a banner protesting what they called President Obama’s acquiescence to the compromises. (They were arrested and charged with trespassing.)