WASHINGTON — Democrats are throwing millions of dollars into TV ads tethering House Republican candidates to Donald Trump all around the country. They say the strategy is bolstering their quest for big gains in the chamber in this November’s elections.

Republicans discount the impact their presidential nominee will have on House races. They say voters distinguish between Trump’s unconventional candidacy and local, familiar congressional hopefuls. And they’re firing back with ads tying Democratic House candidates to Hillary Clinton in Maine, Michigan and elsewhere.

There’s no doubt that Trump’s criticisms of women, Hispanics and others have raised Democrats’ prospects, especially in suburban districts and those with well-educated or minority voters.

The big question is whether that’s enough for an unlikely Democratic gain of 30 House seats, which would give them majority control.