Kelli Ward, who is challenging Mr. Flake in Arizona’s GOP Senate primary in 2018, said that the pardon will help “counter the politically motivated assault on Sheriff Arpaio.

House Speaker Paul Ryan on Saturday criticized President Donald Trump for pardoning a former Arizona sheriff, Joe Arpaio, becoming the highest-ranking Republican to object to the move. “The speaker does not agree with the decision,” said Ryan spokesman Doug Andres. “Law-enforcement officials have a special responsibility to respect the rights of everyone in the United States. We should not allow anyone to believe that responsibility is diminished by this pardon.” The White House didn’t immediately respond to a request for comment about Mr. Ryan’s statement.

On Friday, the White House announced that the president had pardoned Mr. Arpaio, known as an immigration hard-liner who had been sheriff of Maricopa County for 24 years before he lost a re-election bid last year.

As sheriff he took aggressive measures to curb illegal immigration, including hunting people who crossed the border illegally in remote parts of his county, launching workplace raids and conducting traffic stops. In a tweet Friday, the president described Mr. Arpaio as a “patriot” who “kept Arizona safe.”

The pardon is the latest point of friction between the president and Mr. Ryan, who have sparred periodically since the campaign. On Thursday, Mr. Trump sent a pair of tweets faulting Mr. Ryan and Senate Republican Leader Mitch McConnell of Kentucky for their legislative strategy in raising the debt ceiling. By failing to tie the debt-ceiling measure to a popular veterans-affairs bill, the pair missed a chance to resolve the issue and created “a mess,” Mr. Trump wrote. Mr. Ryan, in an interview with CNBC, said he didn’t take offense. “I don’t really take it as going after me,” he said. A spokesman for Mr. McConnell said Saturday the pardon is a “White House question.” Other Republicans also criticized the pardon, including Arizona’s two U.S. senators. Sen. Jeff Flake tweeted that he would have “preferred that the president honor the judicial process and let it take its course.” Sen. John McCain said that in granting the pardon the president “undermines his claim for the respect of rule of law as Mr. Arpaio has shown no remorse for his actions.” Also weighing in was Jeb Bush, the former Florida governor who competed with Mr. Trump for the Republican presidential nomination. Citing Mr. McCain’s statement, Mr. Bush tweeted: “John McCain is right on the mark.” But Rep. Trent Franks, an Arizona Republican, tweeted: “The president did the right thing—Joe Arpaio lived an honorable life serving our country, and he deserves an honorable retirement.” Kelli Ward, who is challenging Mr. Flake in Arizona’s GOP Senate primary in 2018, said in a statement on her Facebook page that the pardon will help “counter the politically motivated assault on Sheriff Arpaio’s heroic efforts to enforce the nation’s #immigration laws.”

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