Senator Lamar Alexander, a Republican from Tennessee and chairman of the Senate Health, Education, Labor and Pension Committee, speaks during a nomination hearing in Washington, D.C., U.S., on Wednesday, Nov. 15, 2017. The Trump administration's pick for solicitor of labor would be charged with overseeing one of the largest government legal shops and have independent authority to file lawsuits enforcing some 180 federal workplace statutes. Photographer: Zach Gibson/Bloomberg Sen. Lamar Alexander, R-Tenn. (Photo: Zach Gibson/BB)

Republican Sen. Lamar Alexander of Tennessee said he won’t run for re-election in 2020, adding to the GOP’s challenges in keeping control of the chamber in two years.

Alexander, a former two-term governor of Tennessee and the current chairman of the Senate Health, Education, Labor and Pensions Committee, said in a statement Monday that after three Senate terms it’s time for someone new to represent the state.

(Related: Lamar Alexander Keeps the Individual Health Rescue Fight Alive)

“The people of Tennessee have been very generous, electing me to serve more combined years as governor and senator than anyone else from our state,” he said. “I am deeply grateful, but now it is time for someone else to have that privilege.”

The departure of Alexander, 78, will open a vacancy atop a Senate panel that covers public schools, colleges, labor rights and the U.S. health care system. Tennessee is a Republican-leaning state, so whoever the GOP nominates would likely start as a favorite to retain Alexander’s seat.

Yet Republicans face challenges in keeping control of the Senate after 2020, so the departure of a popular incumbent is a step back. Republicans picked up two seats in the November elections to gain a 53-47 seat majority when the next session of Congress starts in January. In two years, they’ll have to defend 22 seats, compared with just 12 for Democrats.

Competitive Seats

Republican-held seats in Arizona, Colorado and Maine are considered competitive. Republicans have only one likely 2020 pickup opportunity, in Alabama where Democratic Senator Doug Jones will be seeking re-election in a heavily Republican state.

There are no clear front-runner Tennessee Senate candidates in either party for 2020, said Jennifer Duffy, Senate editor of the nonpartisan Cook Political Report. She said Democrats might look to 2018 gubernatorial nominee Karl Dean, the former mayor of Nashville. State House Minority Leader Craig Fitzhugh is another possibility, she said.

Duffy said that Republican U.S. House lawmakers from the state are likely to consider the race, including Rep. Diane Black, who unsuccessfully ran for governor and will leave office in a few weeks. Beth Harwell, outgoing speaker of the state House, also is a potential candidate, Duffy said.

“I think that there are lots of Republicans who will look at the race,” Duffy said. “Democrats will have a harder time finding a first-tier candidate in a presidential year.”

Former Governor

While governor of Tennessee, Alexander was chairman of the National Governors Association. He served as secretary of Education under President George H.W. Bush.

For six years, he was chairman of the Senate Republican Conference, the No. 3 Republican leadership post.

In the Senate, Alexander worked with Democrats on several key pieces of legislation that became law. In 2015, President Barack Obama signed into law his Every Student Succeeds Act, which replaces the 2001 No Child Left Behind law with more flexibility for states and local districts to bolster low-scoring schools.

He sponsored the 21st Century Cures Act, which was enacted in 2016 to speed approval of drugs and medical devices and increase funding for research into cures for diseases including cancer.

Alexander tried, without success, to bolster the Affordable Care Act with bipartisan legislation to help shore up the public health insurance exchange system.

— Read Lamar Alexander Puts Bipartisan ACA Repair Bill Back in Playon ThinkAdvisor.

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