Control of Senate to Ride on Trump’s Fortunes

As Biden continues to lead in presidential polls, Democrats express confidence in holding their House majority

Democrats appear to have a firm grasp on retaining the House while the Republican-controlled Senate remains up for grabs as the campaign hits the home stretch, with both sides expecting the results to be heavily influenced by how President Trump fares with voters buffeted by the coronavirus pandemic and protests over policing.

The continued strength of Democratic presidential nominee Joe Biden, who leads Mr. Trump in national and several battleground state polls, has kept...