(Bloomberg) -- Election night may already seem like ancient history, but in some parts of the country the midterms are unfinished business. There are House and Senate races still too close to call and there’s the possibility of recounts in some key contests.

Senate Outlook

Senate Republicans are a lock to retain control of the upper chamber, but their margin of victory remains in doubt and may not be established for weeks. The final outcome has implications for Senate Majority Leader Mitch McConnell’s ability to smooth the way for President Donald Trump’s nominations as well as the size of the hurdle Democrats would have to clear to retake the chamber in 2020.

  • The Arizona Senate race between Republican Representative Martha McSally and Democrat Kyrsten Sinema could take weeks to decide. Sinema had a lead of about 9,600 votes on Thursday, according to the Arizona secretary of state. But the Arizona Republic newspaper estimated that as many as 650,000 ballots still are uncounted. McSally’s campaign, in a statement, claimed that "data modeling shows that as remaining ballots are counted, our opponent’s lead will disappear." Meanwhile, the Associated Press reported Republicans filed a lawsuit seeking to limit voters’ ability to clear up signature problems with mailed-in ballots after election day, particularly in urban areas where Sinema has the advantage.
  • Florida increasingly appears headed for a recount in the Senate race, with Governor Rick Scott’s lead over incumbent Bill Nelson narrowing. Democrats are bringing in their election lawyer Marc Elias, and Scott said Thursday night that his campaign is suing the election supervisors of Broward and Palm Beach counties. He also called for the Florida Department of Law Enforcement "to investigate this immediately." Trump, late Thursday, posted a tweet in support of Scott. And Andrew Gillum, who conceded the governor’s race on election night, now sounds ready for a recount as well. State law provides for a machine recount if the margin is less than than 0.5 percent of the vote. If that shows the margin narrows to less than 0.25 percent of the vote, a manual recount is triggered, which should be concluded by Nov. 18.
  • The Mississippi Senate race between incumbent Republican Cindy Hyde-Smith and challenger Mike Espy will go to a runoff on Nov. 27. Hyde-Smith is expected to prevail since conservative Chris McDaniel will no longer be in the race to draw off support.

House Outlook

The margin of the Democratic victory in the House also isn’t settled. As of Thursday, 422 races have been called and Democrats have secured at least 225 seats, a slim seven-seat majority. Whether House Minority Leader Nancy Pelosi can get the 218 votes she needs to return as House speaker could depend on that margin increasing.

Thirteen House races are not yet called so the maximum Democrats could end up with is 238 seats. Based on the vote counts and political trends in the district’s involved, it’s likely that they’ll end up with 230.

These five seats are most likely to flip to Democrats:

  • Dana Rohrabacher appears headed toward losing his re-election bid to Democrat Harley Rouda in California’s 48th District, but the race hasn’t been called. Rohrabacher gained national attention for his support of Russian President Vladimir Putin.
  • Democrat Katie Hill is on track to unseat Los Angeles-area Republican Steve Knight.
  • Mia Love is in danger of losing her 4th District Seat in Utah to Democrat Ben McAdams. Trump mocked Love at his press conference Wednesday for not "embracing" him, but she could still win.
  • Democrat Andy Kim has pulled ahead of New Jersey incumbent Republican Tom MacArthur in the 3rd District. MacArthur brokered a deal to ensure House passage of an Obamacare repeal bill and voted for Trump’s tax overhaul, which raised taxes on some in his state. Kim would be the first Korean-American Democratic member of Congress.
  • Democrat Anthony Brindisi is on the verge of ousting Trump-style Republican Claudia Tenney from her upstate New York district but holds a lead of less than 1,500 votes.

For now, it’s looking like the Republicans will hold onto these eight seats:

  • Representative Chris Collins, who has been indicted on insider trading charges, holds a slim lead over challenger Nate McMurray in New York’s 27th District, which is in the Buffalo area and heavily Republican.
  • Republican Young Kim is leading Gil Cisneros to keep California’s 39th District seat in Republican hands. Kim would be the first Korean-American woman in Congress.
  • Incumbent Republican Mimi Walters is leading the contest against Katie Porter in the California 45th district.
  • Georgia Republican Rob Woodall is ahead in a close race with challenger Carolyn Bourdeaux with less than 1,000 votes separating them.
  • Maine’s Bruce Poliquin, the last Republican in New England, has a slim lead in the 2nd District over challenger Jared Golden.
  • Republican Mark Harris is on track to keep the North Carolina 9th District for the GOP but he holds a less than 2,000 vote lead over Dan McCready.
  • Texas Republican incumbent Will Hurd is barely holding onto a lead over challenger Gina Ortiz Jones in the 23rd district, in southwestern Texas.
  • Moderate Republican incumbent Jeff Denham is slightly ahead of his Democratic opponent, Josh Harder, in California’s 10th district. Denham could become the top Republican on the Transportation and Infrastructure Committee if he wins, making him a player on any infrastructure legislation.

To contact the reporters on this story: Erik Wasson in Washington at ewasson@bloomberg.net;Steven T. Dennis in Washington at sdennis17@bloomberg.net

To contact the editors responsible for this story: Joe Sobczyk at jsobczyk@bloomberg.net, John Harney

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