The battle for control of Congress is intensifying ahead of the November 3 U.S. midterm elections, with Republican campaign groups shifting significant resources toward vulnerable Senate races as Democrats show growing momentum.

Republican super PACs have redirected more than $100 million toward defending Senate seats, including races in Texas, Alaska, Iowa and Ohio. In Texas, President Donald Trump has repeatedly campaigned for Republican Senate candidate Ken Paxton as Democrats seek to make the traditionally Republican state competitive.

The latest Reuters/Ipsos poll adds to Republican concerns: 48% of voters who supported Kamala Harris in 2024 said they were very enthusiastic about voting this November, compared with 30% of Trump voters. The poll also found Harris supporters were more likely to say they were almost certain to vote.

With both parties fighting over a narrow group of competitive races, voter enthusiasm and turnout could become decisive in determining control of the House and Senate.