Why does senator Paine confess in smith goes to Washington?

In "Mr. Smith Goes to Washington," Senator Paine confesses to his involvement in corrupt dealings because he is confronted by the idealistic Jefferson Smith, who represents integrity and the fight for truth. Paine's guilt and the weight of his actions ultimately push him to reveal the truth, highlighting the contrast between Smith's unwavering principles and the corruption prevalent in politics. His confession serves as a pivotal moment in the film, emphasizing themes of morality, accountability, and the potential for redemption.