John Rousselot, the former Republican congressman from California, appears to be the leading candidate to succeed William M. Isaac as chairman of the Federal Deposit Insurance Corp, administration sources said yesterday.

North Carolina banker C. C. Hope Jr. is the administration's first choice to take the Democratic seat on the three-member FDIC board, regulatory sources said. Hope would succeed Irvine Sprague, who worked closely with Isaac during the most tumultuous period in the bank regulatory and insurance agency's 51-year history.

The Reagan administration also apparently has narrowed its list of candidates to succeed C. Todd Conover as Comptroller of the Currency, whose office regulates about 4,700 federally chartered banks.

Sources said that Richard Breeden, the executive director of Vice President Bush's commission on reform of the financial system, and Washington banker James F. Rogers are the leading candidates for the comptroller's job.

Rogers is president of American Security Corp., which is the parent company of the District's second-biggest bank. Rogers is expected to resign from American Security soon, perhaps as early as today, whether or not he is nominated for the comptroller's position.

Washington banking sources said that Rogers and former American Security chairman W. Jarvis Moody ran the $4.1 billion bank company as a team. After Moody resigned last month -- for health reasons -- and was succeeded by Daniel J. Callahan, Rogers' departure was widely expected at the bank.

Isaac and Conover guided the FDIC and the comptroller's office during the most difficult period the U.S. banking industry has faced since the Great Depression. Their successors will face a difficult banking environment too.

The FDIC examines roughly 9,000 state-chartered banks that are not members of the Federal Reserve system and insures deposits up to $100,000 in all but a few hundred of the nation's 14,700 banks.

The banking industry was strained by back-to-back recessions in 1980 and 1981 and was rocked by deregulation, increasing nonbank competition and the Latin American debt crisis. Last summer, the system faced its biggest crisis in five decades when giant Continental Illinois National Bank nearly failed as a result of a worldwide run on its deposits.

Conover and Isaac collaborated to rescue Continental to prevent what they felt could have been a worldwide financial panic. The bank, then with $41 billion in deposits, had big relationships with banks and businesses around the globe.

Today, the banking industry remains in grave difficulty despite several years of strong economic growth. The number of problem banks is continuing to rise, mainly because of the four-year depression in U.S. agriculture. Farm banks are being added to the problem lists faster than non-farm banks are being removed.

Rousselot gained a reputation as a "smart if conservative" representative during his years in Congress, according to a congressional staffer who knows him well. He served on the House Banking Committee and the House Ways and Means Committee.

Hope is vice chairman of First Union Bank in North Carolina.

Both Isaac and Conover plan to stay in their jobs long enough to ensure a smooth transition. Sprague, who was chairman of the FDIC under President Carter, also has promised to stay until his successor is ready.

Sources in the comptroller's office said that Conover, who has met with potential successors, met late yesterday afternoon with American Security's Rogers.