US President Donald Trump speaks at an earlier campaign rally for Texas Republican Senate candidate Ken Paxton at Peterbilt Motors Company in Denton, Texas. (EPA Images pic)

SAN ANTONIO: US President Donald Trump made his third trip to Texas in a month on Wednesday to campaign for Republicans who now face unexpectedly tight midterm election battles as the party seeks to retain control of Congress.

Trump appeared on stage in a packed San Antonio arena with Republican Senate candidate Ken Paxton, who is locked in a close race with Democrat James Talarico. A loss on November 3 would complicate the party's path to retaining its slim Senate majority and mark a major setback in a Republican stronghold.