Some states with tight Senate races are seeing their Obamacare rates climbing next year even more than the average 22 percent increase announced by the Obama administration on Monday, as Republicans use the spikes to try to get the upper hand in a close battle for control of the chamber.

Two states with very tight Senate races are facing big increases: Pennsylvania with 53 percent and North Carolina with 40 percent. Incumbent Sens. Pat Toomey in Pennsylvania and Richard Burr in North Carolina are in close re-election battles.