Democratic seats that are safe or not up for election
seats are too close to call
Republican seats that are safe or not up for election
Vying for power
The longest stretch where Republicans held the White House and the Senate majority was between 1897 to 1913 – half of those years Theodore Roosevelt presided as president. The longest period Democrats had both was 1933 through 1945, during Franklin D. Roosevelt's presidency. Having the White House and a Senate majority improves a party's chances of passing legislation and filling positions such as seats on the Supreme Court that require Senate confirmation. But the most power comes when a party reaches the 60 votes needed to overcome a filibuster.
Key Senate races
Illinois
Democrats are likely to take this seat from Republican Sen. Mark Steven Kirk. Despite Kirk’s attempts to chart a course as a moderate and his early disavowal of Trump, voters in Obama’s old stomping ground appear to favor Rep. Tammy Duckworth, a former Army Black Hawk helicopter pilot who lost her legs after being shot down during the Iraq war.
Wisconsin
Republican Sen. Ron Johnson has gained some ground on former Sen. Russ Feingold, the Democrat, who is running to retake the seat he lost to Johnson in 2010. But Feingold still holds a lead in the race, and the state usually tilts Democratic in presidential election years.
Indiana
With Republican Sen. Dan Coats retiring, Democrats saw an opening here, particularly after Evan Bayh, a popular former governor and senator, who retired in 2011, made a late entry into the race. Bayh has had several stumbles, giving Rep. Todd Young, the GOP candidate, a strong shot in this generally Republican state. The race seems headed for a close finish.
Missouri
GOP Sen. Roy Blunt shouldn’t have to be fighting for reelection in this increasingly red state, but the youthful secretary of state, Jason Kander, has become a breakout candidate and could deliver the seat to Democrats.
North Carolina
Republican Sen. Richard Burr wasn’t supposed to be at risk, but backlash over the September police shooting of Keith Scott and an anti-transgender bathroom law has lured Hillary Clinton to step up campaigning here, giving a boost to Burr’s Democratic challenger, Deborah Ross, a former state legislator and ACLU executive.
New Hampshire
Republican Sen. Kelly Ayotte is facing a tough challenge from Gov. Maggie Hassan in a state that voted for Obama in 2008 and 2012. She’s trying hard to distance herself from Donald Trump, but Hassan has been airing an ad showing a moment in a recent debate in which Ayotte said Trump could be a role model for children – something Ayotte quickly retracted.
Nevada
Senate Minority Leader Harry Reid’s retirement gives Republicans another shot at a seat they’ve been trying to snatch for a long time. Reid is campaigning hard for his hand-picked replacement, Catherine Cortez Masto. The Republican candidate, Rep. Joe Heck, got heckled recently when calling upon Trump to quit the presidential race. He is trailing in some recent polls.
Pennsylvania
Democrats have won the state consistently in recent presidential races and Clinton is leading Trump, but the race between Democrat Katie McGinty, a former environmental adviser to Vice President Al Gore, and Republican Sen. Pat Toomey remains one of the tightest.
Florida
After changing his mind and deciding to run for reelection following his failed presidential run in the GOP primaries, Sen. Marco Rubio has been running ahead of Patrick Murphy, a member of Congress who represents part of Florida's east coast.
Iowa
The popular Sen. Chuck E. Grassley looks safe despite efforts by former Lt. Gov. Patty Judge to make an issue of his refusal, as chairman of the Senate Judiciary Committee, to hold a hearing for President Obama’s Supreme Court nominee, Judge Merrick Garland.
Ohio
Once thought to be a real battleground, Ohio appears ready to reelect Republican Sen. Rob Portman in his race against former Gov. Ted Strickland. Although Trump and Clinton are still in a close battle in this swing state, Democrats are already shifting money to other Senate races.
David Lauter and Thomas Suh Lauder contributed to this project.
Sources: Senate.gov, Times reporting