WASHINGTON (AP) — Pressure is increasing on a Trump administration official to authorize a formal transition process for President-elect Joe Biden.

Republican Sen. Rob Portman of Ohio on Monday called for the head of the General Services Administration to release money and staffing needed for the transition.

Portman, a senior member of the Senate Homeland Security and Governmental Affairs Committee, also said Biden should receive high-level briefings on national security and the coronavirus vaccine distribution plan.

Meanwhile, more than 160 business leaders asked GSA chief Emily Murphy to immediately acknowledge Biden as president-elect and begin the transition to a new administration. "Withholding resources and vital information from an incoming administration puts the public and economic health and security of America at risk,'' the business letters said in an open letter to Murphy.

Among those signing the letter were Jon Gray, president of the Blackstone private equity firm; Robert Bakish, president and CEO of ViacomCBS Inc.; Henry Kravis, the co-chief executive of Kohlberg Kravis Roberts & Co., another private equity giant; David Solomon, CEO at Goldman Sachs; and George H. Walker, CEO of the investment firm Neuberger Berman and a second cousin to former President George W. Bush.

The renewed calls for an official transition came as Biden is building out his administration with key picks for national security and foreign policy roles. Former Secretary of State John Kerry will lead the incoming administration's effort to combat climate change, while Alejandro Mayorkas will be nominated as Homeland Security secretary.

Biden also plans to nominate veteran diplomat Antony Blinken as his secretary of state, according to multiple people familiar with the Biden team's planning.

House Democrats said in a letter to Murphy last week that Murphy's refusal to begin transition activities required by law is having "grave effects." Those effects include "undermining the orderly transfer of power, impairing the incoming administration's ability to respond to the coronavirus pandemic, hampering its ability to address our nation's dire economic crisis, and endangering our national security," Democrats say.

Two House committees, Oversight and Appropriations, are seeking an immediate briefing with Murphy to help lawmakers decide whether to call Murphy and other officials to testify at a public hearing.

Murphy, who was appointed by President Donald Trump, has yet to certify Biden as the winner of the presidential election, stalling the process of officially launching the transition. Trump has publicly refused to accept defeat and has launched a series of court battles across the country making baseless claims of widespread voter fraud and seeking to overturn the election results.

Portman, a Trump ally, said it was "only prudent' for GSA to begin the transition process immediately.

"Donald Trump is our president until Jan. 20, 2021, but in the likely event that Joe Biden becomes our next president, it is in the national interest that the transition is seamless and that America is ready on Day One of a new administration for the challenges we face,'' Portman wrote in an op-ed calling for the transition to begin.

When Murphy ascertains that Biden won, it will free up money for the transition and clear the way for Biden's team to begin placing transition personnel at federal agencies. Trump administration officials also say they will not give Biden the classified presidential daily briefing on intelligence matters until the GSA makes the ascertainment official.

Murphy spent most of the last 20 years honing a specialized knowledge of government procurement through a series of jobs as a Republican congressional staffer and in senior roles at the GSA and the Small Business Administration. She did shorter stints in the private sector and volunteered for Trump's transition team in 2016.

She worked her way up through partisan politics to a position that isn't in the spotlight, but is undeniably a powerful cog of governance.

"I am not here to garner headlines or make a name for myself," Murphy said at her Senate confirmation hearing in October 2017, "My goal is to do my part in making the federal government more efficient, effective and responsive to the American people."