West Virginia Gov. Jim Justice is becoming a Republican, but that doesn't mean he'll have the warmest of welcomes in his new political party.

West Virginia's Republican Party attacked Justice on Twitter on Thursday less than two hours before news broke that he was switching parties at a Thursday evening rally in the state with President Trump.

Low-Energy @WVGovernor Refuses To Stop Millions Of $$ In Contracts To Companies Who Cheated WV Taxpayers. Sad!https://t.co/Nf1QvGaWl3 — WVGOP (@WVGOP) August 3, 2017

A senior GOP operative confirmed to The Hill on Thursday afternoon that Justice, who was wooed by both parties before deciding to run as a Democrat last year, would be announcing his decision to become a Republican at Trump's rally.

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Justice's decision is a surprise, considering the Democratic Governor's Association spent more than $1 million to get him elected. He's the only billionaire in West Virginia, and is the chief executive officer at dozens of companies, many in the coal industry.

Trump teased Justice's announcement earlier on Thursday.

“We’re going to have a very big announcement, which will be very exciting I think for the media and everyone else,” Trump said Thursday morning. “I believe I’ll be making it in West Virginia, so that will be very exciting.”