The strength of Democrats' majorities in the House and Senate remains undetermined one week after Election Day as more than a dozen races are still too early to call Tuesday.

Democrats are on track to hold 54 Senate seats in January, but could pick up one or two more from Republicans as votes are counted in Alaska and Mississippi.

With 255 seats in the House, Democrats will have their largest majority elected to the chamber since the 2008, with the potential to pick up several more seats as the remaining races are called.