(idiomatic) action that was taken too late and too feeble to be of any use, not enough to be useful
Examples
The government's attempts at reform were a day late and a dollar short.
Although it's the 6th largest state, an Electoral College powerhouse, and a state bitterly fought over in presidential elections, Pennsylvania has little or no influence on the nominees for president. When it comes to nominating presidents, Pennsylvania is always a day late and a dollar short. (Pennsylvania's 'Primary Problem' by G. Terry Madonna and Michael Young, January 29, 2007)