Watch: Trump promotes GOP tax bill in Pennsylvania

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President Donald Trump traveled to the Pittsburgh, Pa., area on Thursday to tout the newly enacted Republican tax overhaul. The trip was also designed to give Trump an opportunity to publicly endorse Republican congressional candidate Rick Saccone, who is running in a special election to be held in March.

Earlier in the day, the president caused some confusion about the purpose of the trip, when he tweeted, "Will be going to Pennsylvania today in order to give my total support" to Saccone. On its face, the tweet suggested that the president's trip was for the purpose of campaigning for Saccone.

The White House later clarified that the point of the trip was for Trump to speak about tax reform, and not to campaign for Saccone. The reason this matters is that official White House funds cannot be used to pay for campaign trips, only for official presidential duties.

If the purpose of the trip were political, then either the Republican National Committee or the Trump campaign would be expected to pay the costs.

On Capitol Hill, Congress raced to come up with a plan to keep the government open past Friday, the latest deadline for a government spending bill to avert a partial shutdown. The White House said Trump backs the bill.