Anthony Zurcher: Democrats eye sweeping gains and reshaping of political map

This is already shaping up to be a very good night for Democrats, with much of the vote counted in the eastern United States and polls closing in key Midwestern battleground states.

Two Senate races that a year ago were thought to be battlegrounds have turned out to be slam dunks for the Democrats - Jon Ossoff's re-election race in Georgia and the open Republican-held seat in North Carolina.

That North Carolina contest, where former Democratic Governor Roy Cooper bested Republican Party insider Michael Whatley, was the first of the four pick-ups Democrats need in order to wrest control of the Senate.

Attention has now turned to Republican-held Senate seats in Texas, Kansas and Ohio, where counting is taking place.

In South Carolina, the BBC's US partner CBS News is rating the Senate race as leaning Democrat, which would be an earth-shaking result.

If you look at key races in House of Representatives, there are other encouraging signs for Democrats.

In Florida, Republicans in the state legislature had redrawn the boundaries of three Democratic-held seats to make it much easier to for them to win.

They lost all three.

Other House races in the state, where Republicans expected to win by comfortable margins, have turned out to be dogfights.

Democrats flipped an open seat in western North Carolina, for instance, and appear in position to make gains in Virginia, Kentucky and Indiana.

In races considered toss-ups across the east, Democrats are poised for the kind of victories that will help secure a House majority for the first time since 2022.

They're doing it on the back of high Democratic turnout, particularly by black voters in the south, and winning back Hispanic voters in Florida who had supported the Republicans just two years ago.

In majority black South Carolina counties, Democratic Senate candidate Annie Andrews is significantly outperforming Kamala Harris's presidential numbers in 2024.

And in Miami-Dade County, which Trump carried that year, Democratic candidates are back on top.