WASHINGTON: A record 47.9 million Americans have already voted in next week's US midterm elections, with participation surging in key battleground states and registered Democrats outpacing Republicans, figures showed on Friday.

The University of Florida's Election Lab had recorded 47,922,669 early votes nationwide by midday, surpassing the previous midterm record of 45.9 million cast ahead of Election Day in 2022.

The surge is especially pronounced in states with fiercely contested Senate races that could determine control of the chamber during the final two years of President Donald Trump's presidency.

In Texas, more than six million people had voted early by Wednesday, according to official figures, with in-person turnout running about 50 per cent ahead of the same stage in 2022.