Senior US Republicans say Prosecuting former President Donald Trump will be a politically motivated move by his opponents.
On Saturday, Mr Trump said his arrest could happen next week, based on media reports.
But Democrats have said no-one is above the law and accused Mr Trump of recklessly stoking political divisions.
The case focuses on alleged hush money paid on Mr Trump’s behalf by his lawyer to porn star Stormy Daniels ahead of the 2016 presidential election.
The 76-year-old is also the subject of several other separate inquiries, although he has not yet been charged in any and denies wrongdoing.
Mr Trump has pledged to continue his campaign to become the Republican nominee in the 2024 presidential election, even if he is indicted.
It is not yet known if he is going to be criminally charged.
BBC reports that former US vice-president Mike Pence and the most senior Republican in the US Congress, Kevin McCarthy, have both spoken out against any criminal prosecution.
Mr Pence said Manhattan district attorney Alvin Bragg, who is a Democrat, was carrying out a “politically charged prosecution” against Mr Trump.
“I’m taken aback at the idea of indicting a former president of the United States, at a time when there’s a crime wave in New York City,” Mr Pence said.
“The fact that the Manhattan DA [district attorney] thinks that indicting President Trump is his top priority, I think, just tells you everything you need to know about the radical left in this country,” he stated.
Speaker of the US House of Representatives, Kevin McCarthy called the investigation “an outrageous abuse of power by a radical DA”.
In a tweet, he also promised to investigate whether federal money was being used to interfere in elections “with politically motivated prosecutions”.
Democrats, who control both the executive and Senate, accuse Mr Trump of stirring up political divisions with his claims of possible arrest.
Mr McCarthy’s predecessor as House Speaker, Nancy Pelosi, echoed the sentiments of many of her co-Democrats, adding that Mr Trump’s remarks were “reckless” and designed to “keep himself in the news and to foment unrest among his supporters”.
“He cannot hide from his violations of the law, disrespect for our elections and incitements to violence. Rightfully, our legal system will decide how to hold him accountable,” she wrote on Twitter.
Writing by Fany Olumoye; Editing by Julian Osamoto and Tony Okerafor