The race to stop ObamaCare before Americans can officially sign up this fall for the government-backed health insurance intensified Sunday with two of the movement’s biggest champions confident they will succeed but acknowledging it will take a “tsunami” of support.

Texas Republican Sen. Ted Cruz, a Tea Party-backed lawmaker at the center of the effort to “defund” ObamaCare, said the fight will play out in the weeks before the Oct. 1 signup date and that success will require a grass-roots effort in which Americans across the country “demand” their elected officials “do the right thing.”

“This fight is likely to heat up in the month of September,” Cruz told CNN’s “State of the Union.” “That’s going to be when the battle is engaged.”

Cruz is joining Heritage Action for America, the advocacy arm of the conservative Heritage Foundation think tank, to get lawmakers after they return to Capitol Hill next week to separate out ObamaCare from a temporary spending bill to keep the federal government running, then vote in favor of the spending bill to avoid a politically unpopular government shutdown.