GOP Rep. Chris Collins, one of President Donald Trump's earliest backers in Congress, suspended his reelection campaign on Saturday, in the wake of insider trading allegations that resulted in his dramatic arrest this week and may derail his entire career.

Only days ago, the congressman — who's ensnared in a case involving the sale of stock on information that was not made public — was vowing to run for another term, calling the charges "meritless."

Yet in a statement on Saturday, the embattled New York Republican who represents the state's 27th Congressional district said that "after extensive discussions with my family and my friends over the last few days, I have decided that it is in the best interests of the constituents of NY-27, the Republican Party and President Trump's agenda for me to suspend my campaign for re-election to Congress."

Collins' district, which is in the Western part of the Empire State, is considered heavily Republican. Yet his travails come at a time when Democrats are on the offensive ahead of the midterm elections, and generic polls show them widely favored to recapture the House of Representatives at the very least.

"Democrats are laser focused on taking back the House, electing Nancy Pelosi Speaker and then launching impeachment proceedings against President Trump," Collins' statement read.

"They would like nothing more than to elect an 'Impeach Trump' Democrat in this District, which is something that neither our country or my party can afford," he added.

Collins tweet

The congressman may have trouble getting his name removed from the ballot ahead of the November elections. New York's labyrinthine laws make it difficult for a candidate to have his or her name revoked, even for reasons that include death, disqualification or asking for removal.

The latter has several deadlines, all of which Collins appears to have missed — meaning it's entirely possible his name could appear on the ballot, even under indictment. Among the slim options available to Collins and the state GOP involve his moving out of his district, or being nominated for another office.

"Given the circumstances, it was probably the best decision for his family and for the residents of the 27th Congressional district," said Ed Cox, the New York GOP delegation chair. "In the coming days, we will be working closely with local party leaders to determine the best course of action. We wish Chris and his family the best."

At least one candidate was prepared to replace Collins. Erie County Comptroller Stefan I. Mychajliw declared himself in the running, saying in a statement posted to Twitter that he would "work to earn the trust of" GOP officials that could possibly get him the Republican nomination.

Nate McMurray, Collins' Democratic challenger, said in a statement provided to NBC News that the congressman should resign his seat and that his campaign suspension symbolized "corrupt party machine politics."

McMurray added that "this tragic tale is yet another example of how a corrupt party machine has consistently betrayed the people of the 27th Congressional District."

Collins, a wealthy businessman, was first elected to to the House of Representatives in 2012. He immediately became one of the 10 richest lawmakers, with an average net worth of nearly $60 million, according to OpenSecrets.

However, his business acumen has landed him in hot water, with federal authorities nabbing him on insider trading charges on Wednesday. The congressman stands accused of selling shares of an Australian biotechnology company.

Collins is accused of funneling nonpublic information about a failed drug trial to his son before the company announced it publicly. Collins' son Cameron was also charged in the indictment, and is accused of dumping more than a million shares of the company's stock ahead of a steep plunge in its price.

--CNBC's Brian Schwartz and Kevin Breuninger contributed to this article.