WASHINGTON — The White House has tapped a corporate cyber security expert and former Bush administration official to lead the effort to shore up the country’s computer networks and better coordinate with companies that operate 80 percent of those critical systems.

Howard A. Schmidt, a former eBay and Microsoft executive, will become the government’s cyber security coordinator, weathering a rocky selection process that dragged on for months, as others turned the job down.

In a letter posted on the White House web site today, John Brennan, assistant to President Barack Obama for homeland security and counterterrorism, said Schmidt will have regular access to the president and play a vital role in the country’s security.

Schmidt’s selection comes more than 10 months after Obama declared cyber security a priority and ordered a broad administration review.

A senior White House official said Obama was personally involved in the selection process and chose Schmidt because of his unique background and skills. Schmidt will have regular and direct access to the president for cyber security issues, the official said. The official spoke on the condition of anonymity to discuss the selection process.

Obama released the findings of the cyber security review nearly seven months ago, vowing that the White House would name a cyber coordinator to deal with one of the “most serious economic and national security challenges we face as a nation.”

U.S. government computer systems are being attacked or scanned millions of times a day. Hackers and cyber criminals pose an expanding threat, using increasingly sophisticated technologies to steal money or information, while nation-states probe for weaknesses in order to steal classified documents or technology or destroy the networks that run vital services.

Corporate computer security leaders have openly expressed frustration with the White House as movement on the job post stalled.

At the same time, cyber experts and potential job candidates have complained that the position lacks the budgetary and policy-making authority needed to be successful. Schmidt will report to the National Security Council and closely support the National Economic Council on cyber issues.

Schmidt’s selection suggests that economic and business interests in the White House held more sway in the selection process.

Schmidt, president and CEO of the Information Security Forum, a nonprofit international consortium that conducts research in information security, has served as chief security officer for Microsoft and as cyber security chief for online auction giant eBay. He was reportedly preferred by Lawrence Summers, director of the economic council.

Roger Thornton, a cyber security expert and chief technology officer for Fortify Software, praised the choice. He said Schmidt understands the technology, has broad management experience and has worked well within the political arena, a key requirement for the White House post.

“I think he would be able to get people to compromise and move things forward,” said Thornton.

Considered an expert in computer forensics, Schmidt’s roughly 40-year career includes 31 years in local and federal government service, including a stint as vice chairman of President George W. Bush’s Critical Infrastructure Protection Board. He also was for a short time an adviser to the FBI and worked at the National Drug Intelligence Center.

Congress members, business leaders and cyber security experts have called for a more coordinated effort by the federal government to monitor and protect U.S. systems and work with the private sector to insure that transportation systems, energy plants and other sensitive networks are equally protected.