Senator Sherrod Brown has spent his decades in Congress establishing a track record as a populist champion on economic issues. But in the closing days of his re-election race, abortion has become a key emphasis.

COLUMBUS, Ohio (AP) — Three-term Democratic U.S. Sen. Sherrod Brown of Ohio faces perhaps the toughest reelection challenge of his career Tuesday in the most expensive Senate race of the year as control of the chamber hangs in the balance.

Sherrod Brown's 18-year Senate career ended Tuesday after the most expensive non-presidential race in history. Here are four takeaways.