The Republican plans to pick off five Democratic-held congressional seats in Texas once seemed like a sure thing. Not anymore.

Jensen Huang, once almost unknown in Washington, this week won a lobbying victory that could be worth billions of dollars to the semiconductor giant he co-founded, Nvidia.

In New Hampshire, progressives are facing strong headwinds in a race to replace retiring Sen. Jeanne Shaheen, with political outsider Kashima Manzur fighting an uphill battle against a four-term ...