By Jon Hilsenrath and Nick Timiraos

When she led President Clinton's Council of Economic Advisers in the late 1990s, Janet Yellen confided to her husband, economist George Akerlof, about the challenges she faced navigating Washington's political storms.

Those storms are about to become Ms. Yellen's headache again. As President-elect Joe Biden's pick for Treasury Secretary, Ms. Yellen is looking at the most political role she has had in nearly three decades of high-profile policy making. Her job will be to formulate and defend Mr. Biden's policies at a time when the economy is at a crossroads and the capital is deeply polarized.

Tough debates loom about how much more the government should borrow and spend to advance a recovery that is slowing and vulnerable as Covid-19 spreads, but also is poised to bounce back if vaccines are successfully and quickly distributed.

Ms. Yellen's resume was a draw for Mr. Biden. No past Treasury secretary has served both as leader of the Federal Reserve, which she did from 2014 to 2018, and head of the President's Council of Economic Advisers, her job from 1997 to 1999 in the Clinton administration.

Yet her previous experiences with Washington politics were insulated by comparison with the task at hand. Compared with the Treasury Department, the Fed is a cloistered and academic institution. At Treasury, politics is often one of the first considerations.

Progressives in the Democratic Party are pushing for aggressive new spending programs. Republicans appear poised to push for spending restraint. And new administrations often involve their own factions. President Trump's team sparred over trade, and President Obama's over spending and deficit reduction. Assuming she is confirmed as Treasury Secretary, Ms. Yellen will be at the center of it all.

"Treasury is designed to generate opinions on hundreds, thousands of different questions, many of which are known and others that arise in completely unsuspected ways," said Nathan Sheets, a former Obama administration Treasury official and Fed economist. "The saying is that the Treasury moves 10 times faster than the Fed, and the White House moves 10 times faster than the Treasury."

As Treasury secretary, Ms. Yellen would oversee a bureaucracy that handles matters ranging from tax collection to the implementation of international sanctions to the U.S. dollar policy, issues she didn't publicly address in detail during her long career at the Fed.

Ms. Yellen's relationships with congressional Republicans have at times been strained. When she went to Capitol Hill for meetings with lawmakers in her first year as Fed chairwoman, she tended to focus on Democrats, a course she later corrected to address frictions with congressional Republicans. GOP lawmakers routinely pressed her on a range of issues, including allegations of leaks from the central bank about interest rate decision-making.

Republicans also were rankled by her attention to matters such as inequality and the participation of women in the workforce. It seemed to some a diversion from issues the Fed was mandated by Congress to address: unemployment and inflation.

"You're sticking your nose in places that you have no business to be," then- Rep. Mick Mulvaney of South Carolina said at a 2015 hearing.

In the end it turned out there were links between unemployment, inequality and workforce participation. As the jobless rate fell in recent years, women were drawn into the labor force and Black unemployment rates hit lows not seen before -- among President Trump's signature achievements.

On the international front, Ms. Yellen is poised to play a significant role in Mr. Biden's planned efforts to strengthen ties to traditional U.S. allies in Europe, North America and Asia. As Fed chairwoman and before that vice chairwoman, Ms. Yellen was one of the central bank's point people in international finance gatherings for nearly a decade. In the process she built a network of connections with central bankers and finance ministers around the world.

An exception might be China. The Trump administration has imposed trade tariffs on imports from China that Mr. Biden doesn't seem eager to unwind. A range of U.S. grievances with China remain unresolved, including its subsidies to state-owned enterprises and competition for new technologies with significant national-security implications.

"We have very difficult issues that lie ahead" with China, Ms. Yellen said in Hong Kong in January.

Ms. Yellen, a Democrat, likely wouldn't be in her current position if Mr. Trump had offered her a second term as head of the Fed. He considered her, approving of her inclination to keep interest rates low, but chose Republican Jerome Powell instead. Mr. Trump suggested to associates that one of his concerns was that the roughly five-foot-tall Ms. Yellen might be too short to convey stature, according to people familiar with the matter. The White House declined to comment.

Raised in a Brooklyn brownstone by a mother who kept meticulous records of the family's stock portfolio and a physician father who made house calls, Ms. Yellen was an A student known for prodigious note-taking.

As a Ph.D. student at Yale in the 1970s, she was a devotee of James Tobin, a Nobel-winning economist who followed the traditions of John Maynard Keynes, a believer in a strong role for government in economic downturns. One of her small failures in life was starting a textbook that she didn't finish based on her notes of Mr. Tobin's classes. The notes themselves became popular with other graduate students.

Ms. Yellen would spend her academic career focused on labor markets and questions such as: How come in a recession companies lay off workers instead of just cutting their salaries? What's the government's role in addressing the dislocations that come with these layoffs?

By the time she came to Washington in the mid-1990s to serve as a Federal Reserve governor, Ms. Yellen had been molded as a textbook left-of-center economist. She saw unemployment as deeply damaging to workers and believed in a muscular role for the government to address it. However, she also saw practical limits: If unemployment got too low it could spark inflation, and if the government's debt got too big it could drive inflation higher, push up interest rates and slow growth.

Ms. Yellen prepares for tasks meticulously and doesn't particularly like surprises or risks. She tends to arrive hours early for flights to avoid mishaps and to ensure choice space in overhead compartments. When she was a guest at a White House Correspondents' Association dinner in 2014, she was the first person to arrive at a ballroom that seats thousands.

"When Janet was at the Fed, I supported her as much as possible by taking over household duties," said her husband, Mr. Akerlof, in a bio for the Nobel prize in economics he received in 2001. "Later when she was at the White House my role in providing psychological support in the daily political storms was yet more important." He added that they agreed on most issues, though he was more skeptical than she was on the merits of free trade.

Ms. Yellen's main test at Treasury will involve spending and debt.

The experience of the past couple of decades has called into question a central premise of economics: that rising government debt-loads push up interest rates and crimp private investment. Debt has been soaring, but interest rates have fallen and inflation has remained low, with no obvious negative effects on private investment.

The question for Ms. Yellen is how far to push U.S. borrowing. As Treasury Secretary one of her main jobs is to raise the money that funds the government. That comes mainly through changes in tax policy or increased borrowing.

The federal budget deficit tripled to $3.1 trillion in the fiscal year ended Sept. 30. Republicans pushed back against a big price tag for more Covid-19 rescue programs during the summer. They seem poised to resist even harder with a Democrat in the White House.

Mr. Biden has expressed support for the $2.2 trillion measure passed by the House, led by Speaker Nancy Pelosi (D., Calif.), on Oct. 1. He has also endorsed many of the provisions included in the $3.4 trillion Heroes Act the House passed in May. Moreover, he proposes $2 trillion in spending on climate programs.

Many economists today say a bipartisan impulse to curb spending over debt concerns in the years following the 2008 financial crisis hampered the last recovery. Democrats aim to avoid a repeat of that.

"This is not a good time to have fiscal policy switch from being accommodative to creating a drag," Ms. Yellen said in a September interview with The Wall Street Journal. "That's what happened [last decade], and it retarded the recovery."

She said low inflation has increased the need for and lowered the risks of aggressive monetary and fiscal policy. "There is a huge amount of suffering out there. The economy needs the spending," Ms. Yellen said.

Another conclusion she has drawn from years of study as a labor economist and then years more as a policy maker: High unemployment imposes large and lasting costs on American households. As chairwoman and in other positions at the Fed, she often pushed the central bank to hold interest rates down to spur growth and hiring. Low rates encourage borrowing, spending and investment.

She also saw limits to how far the Fed could go to stimulate growth. Ms. Yellen urged Alan Greenspan to raise rates in the 1990s to stave off inflation, advice the Fed's then-chairman ignored. As head of the central bank herself in 2015, she raised interest rates that had been held at near zero for years.

At the Treasury, her lever won't be interest rates, it will be borrowing. Ms. Yellen has argued strongly for more deficit-financed government spending since the pandemic and related restrictions triggered a severe economic downturn.

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11-24-20 2118ET