Mr. Jackson landed in the race unexpectedly. Democrats are hoping he can unseat Susan Collins, a Republican, in their bid to retake the Senate.

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Mr. Paxton, the Texas attorney general now running for the U.S. Senate, was accused of abusing the power of his office to protect a campaign donor. He was acquitted on all counts.

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David Maxwell was among the staffers in the Texas attorney general’s office who accused Ken Paxton of abusing the power of his office, allegations that led to his impeachment. Mr. Paxton was acquitted.

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