A member of the Republican National Committee, fearing primary challengers to President Trump in the wake of incoming GOP Sen. Mitt Romney's scathing op-ed, is urging fellow committee members to change the rules to thwart intra-party threats to Mr. Trump in 2020.

In an email obtained by CBS News, Jevon O.A. Williams, the national committeeman for the Virgin Islands, urged fellow elected RNC members Tuesday night to push for an "unprecedented" rule change in the wake of the Romney op-ed's "calculated political treachery." Williams wants to close "loopholes" in the nomination in a way that would make it tougher for even token challengers to Mr. Trump to enter the fray. The Washington Examiner first reported the letter.

Specifically, Williams urged fellow RNC members to change Rule 40, which requires a candidate for the nomination to garner support from a majority of delegates in at least five states or territories in order to be placed on the nominating ballot at the Republican National Committee Convention. Williams also called for a resolution to declare Mr. Trump the presumptive nominee in 2020, calling for both of those moves to take place at an RNC winter meeting later this month.

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"While President Trump would win re-nomination it wouldn't come quick and it wouldn't be inexpensive. Any contested re-nomination campaign—even a forlorn hope—would only help Democrats," Williams wrote. "Accordingly, I am asking for your support to take the unprecedented step of amending the rules to close loopholes in the re-nomination campaign, including Rule 40."

The email was sent to RNC members two hours after Romney, who has yet to be sworn into office, published an arresting op-ed in the Washington Post titled, "The president shapes the public character of the nation. Trump's character falls short." Romney argued that Mr. Trump has failed to live up to the mantle of his office in the last two years, and America's standing on the international stage is worse off because of it. The op-ed offered a glimpse of how Romney, who has criticized Mr. Trump in the past, might maneuver being a Republican senator under a polarizing president.

The op-ed prompted visceral responses from Mr. Trump's staunchest defenders — including Ronna McDaniel, the chairwoman of the RNC who is Romney's niece and dropped her maiden name -- Romney -- reportedly to appease Mr. Trump. McDaniel, without naming her uncle, blasted the "incoming Republican freshman senator" for his criticism of the president.

POTUS is attacked and obstructed by the MSM media and Democrats 24/7. For an incoming Republican freshman senator to attack @realdonaldtrump as their first act feeds into what the Democrats and media want and is disappointing and unproductive. https://t.co/ArhI7Bi7bo — Ronna McDaniel (@GOPChairwoman) January 2, 2019

Williams' proposal to thwart challenges to the incumbent president comes as some states also look to fend off challenges to him. CBS News' Caitlin Huey Burns has reported some of Mr. Trump's supporters in early states, including South Carolina and New Hampshire, are looking into allowing the Republican party to simply endorse him without holding primary contests.

The Iowa caucuses are scheduled to take place in early February 2020.

Here is the full text of the email sent to RNC members, as obtained by CBS News. Williams did not immediately respond to a request for comment.