Some of the country’s best-known corporations are nervously grappling with what role they should play at the Republican National Convention, given the likely nomination of Donald J. Trump, whose divisive candidacy has alienated many women, blacks and Hispanics.

An array of activist groups is organizing a campaign to pressure the companies to refuse to sponsor the gathering, which many of the corporations have done for the Republican and the Democratic Parties for decades.

The pressure is emerging as some businesses and trade groups are privately debating whether to scale back their participation, according to interviews with more than a dozen lobbyists, consultants and fund-raisers directly involved in the conversations.

Apple, Google and Walmart are among the companies assessing their plans for the convention, which will be held July 18 to 21 in Cleveland.