WASHINGTON (AP) — Republicans are “in a demographic death spiral” and will fail in their effort to win the presidency if the party blocks an immigration overhaul, a leading GOP senator said Sunday.

Sen. Lindsey Graham, the South Carolina Republican who helped write a bipartisan immigration bill under debate in the Senate, said conservatives who are trying to block the measure will doom the party and all but guarantee a Democrat will remain in the White House after 2016’s election.