Mitt Romney returned to the political stage Tuesday night in New Hampshire and warned fellow Republicans against a government shutdown, which he said would bring dire human and political consequences.

The 2012 GOP presidential nominee waded into the policy fight over possibly defunding President Obama's signature health-care law in the budget battle set to resume in September. Romney rejected a strategy proposed by leading congressional Republicans -- including Sen. Marco Rubio (R-Fla.), a leading Romney surrogate last year -- who are threatening not to pass a year-end budget bill if it includes funding for the health-care law.