WASHINGTON, D.C. — U.S. Sen. Rob Portman, R-Ohio, has called on the White House to begin the transition to President-elect Joe Biden’s administration.

In a guest column published in the Cincinnati Enquirer on Monday, Portman, who pointed out that he served as a co-chair of Trump’s campaign in Ohio, broke with his party’s leader called for the country to “move forward” on the post-election process.

The Associated Press and major broadcasts networks called the election for Biden, the former Democratic vice president, on Nov. 7, after four days of vote tabulation following the election.

In the following three weeks, Trump has refused to concede the race, which he has insisted he “won” and declared the election “rigged.”

Portman said while there have been instance of some irregularities, which he said “there have been in every election,” he did not see any evidence of widespread fraud that would change the election result.

“I voted for President Trump, was a co-chair of his campaign in Ohio, and I believe his policies would be better for Ohio and the country,” Portman said. “But I also believe that there is no more sacred constitutional process in our great democracy than the orderly transfer of power after a presidential election. It is now time to expeditiously resolve any outstanding questions and move forward.”

Portman said all disputes should be resolved by the Dec. 8 deadline for states to certify their electors.

“Going past that deadline would cause unprecedented uncertainty and raise serious constitutional questions,” Portman said.

Portman’s comments, three weeks after Election Day, were his first to concede that Biden had won and came as states began certifying their results for selection of electors.

The senator also said the U.S. General Services Administration “should go ahead and release the funds and provide the infrastructure for an official transition, and the Biden team should receive the requested intelligence briefings and briefings on the coronavirus vaccine distribution plan.”

To date, the GSA, under direction of the White House, has refused to do so.

Portman follows Ohio Gov. Mike DeWine, who has said “Joe Biden is the president-elect” and has also called for the transition to begin.

DeWine had said Trump had a right to pursue legal challenges to the election, but said the result is unlikely to change.