Only people unfamiliar with Trump's "incursion" into the Republican Party would be surprised by this.
Trump has been an off-again, on-again Republican for years. He has supported candidates of both Parties for years. Hell, according to one report found here:
President Donald Trump's alliance with Democrats over raising the debt ceiling is nothing new.
www.newsweek.com
He donated more money to Democrats than Republicans for decades.
When he threw his hat into the ring in 2016 he was opposed by 17 Republican contenders who invariably attacked him as an outsider.
When he won the election, he had almost NO support from Republican Senators (several resentful at having lost the Primaries), and only the support of the Tea Party Republicans in the House during the first two years of his Administration.
Why else was he unable to get any of his policy objectives except for a tax cut past the Senate, especially when it came to defanging Obamacare, when Republicans still controlled both Houses?
RINOS like McCarthy will say anything to maintain relevance and office. IMO most long-term members of Congress in both parties are beholden to those various special interests who control donations for future campaign efforts. Who also have the ability to provide insider trading info, and subsequent cushy jobs when it's time for a Congress-critter or a member of the Bureaucracy to "retire."
So what's the "big news" about this two-faced politician supposed to mean in reality? Fair weather friends will be friends only when it suits their needs.