In "House of Cards", Frank Underwood wants some energy bill to pass, but his wife is pressured by SandCorp into undermining him and getting two representatives to vote against the bill, which is a major blow to Peter Russo's campaign. However, later on it seems that Underwood wanted Russo to fail from the start, and the bill's failure seems to be a critical part of Russo's failure. What interest did Frank have in the bill's success if he wanted Russo to fail? The following are not answers:
He wanted Russo to stay viable until the end. Since Russo dies within 48 hours, which seems to be precisely timed by Underwood, the bill doesn't seem to make a difference. Assuming Russo was a dead man either way, the bill's failure actually helps Underwood by giving Russo more motive for suicide.
He had a personal stake in the bill. His only personal stake was Russo's success. He actually lost if the bill passed since his wife got screwed by SandCorp. We can see in their conversation earlier in this episode that his personal investment in the bill is entirely limited to the Russo campaign.
He wanted to maintain his own reputation as someone who could whip the bill into passage. Underwood wouldn't have taken the risk on the bill just for the sake of passing another bill. He needs another motive, otherwise he would have killed it before his own reputation was on the line.