G.O.P. Plans to Drop Presidential Primaries in 4 States to Impede Trump Challengers

The Trump campaign pointed out that in 1992, when President George Bush was seeking re-election, Republicans canceled primaries in eight states, and in 2004, when President George W. Bush was running again, they canceled 10.

The campaign also pointed out that in 1996, when President Bill Clinton was running for a second term, Democrats canceled primaries in eight states, and in 2012, when President Barack Obama was running, they canceled 10.

“Whether or not to hold a presidential primary is a decision made by our state executive committee every four years,” said Drew McKissick, the chairman of the South Carolina Republican Party. “There is strong precedent on the part of both parties to not hold a primary when they control the White House.”

Mr. Weld acknowledged the precedent but said the Trump campaign was taking it a step further.

“This year, the Trump people tried to cancel the first-in-the-nation primary in New Hampshire,” he said. “They did not succeed, but it shows you the lengths it will go to.”

But with the potential for more Republicans to enter the race — Mark Sanford, former governor and congressman from South Carolina, has been toying with a run — political strategists said there was also a case for the White House to confront the challengers head-on.

“Our policy in the past has always been, you’re an incumbent president, you have certain advantages and you’ll probably be nominated again, but go out and win it,” said Ed Rollins, the national campaign director for President Ronald Reagan’s 1984 re-election effort.

For a year, Mr. Trump’s advisers have made moves to block any challenger from gaining traction, saying that incumbents who have faced debilitating primaries have gone on to lose in the general election, as President Jimmy Carter did in 1980 after a strong challenge from Senator Edward M. Kennedy.