Republican groups and megadonors have begun spending in at least 39 U.S. House races since September 1 after internal polling showed previously safe seats could be vulnerable in the November 3 election. The new spending is appearing in advertising reservations and campaign finance filings, including districts that Donald Trump won by double digits and where Republicans still lead in public polls. Republicans hold a 218-214 House majority, with one independent caucusing with Republicans and two vacancies; Democrats need a net gain of at least four seats to take control next year. Party leaders are using their financial advantage to defend incumbents amid economic pressure in agricultural states, while Republican groups have reserved at least $888 million in advertising compared with $666 million for Democrats. Republican-leaning super PACs spent about $309.7 million since Labor Day, nearly twice the $174.2 million spent to support Democrats. The spending push includes $1.5 million for Representative Bryan Steil in Wisconsin, $131,107 for Representative Gregory Murphy in North Carolina and about $2 million to support Representative Monica De La Cruz in south Texas, whose race was moved from lean Republican to tossup by Cook Political Report.