Who will win the House? The outstanding races to watch

The party that will control the US House of Representatives for the next two years is currently unknown.

All 435 seats in the lower chamber of Congress were up for votes this year, and it may take days to get final results and see if Republicans will keep their slim majority. That would put the party in control of Congress and the White House when President-elect Donald Trump is sworn in in January.

Democrats, meanwhile, are hoping that the last votes trickling in in a handful of tight races will be enough to give them a majority in the House.

A party needs 218 seats to take control. As it stands on Wednesday, Republicans have 197 and Democrats 188.

Here are some of the races that have yet to be called.

Democrats are closely monitoring five seats in California as crucial to winning back the House.

Challengers are hoping to defeat the incumbent Republicans and flip the seats blue, but initial polling shows incumbents holding onto their seats by narrow margins.

The key races to watch are:

• California's 45th: Republican Congresswoman Michelle Steel, the incumbent, is currently leading against Democrat Derek Tran with 66% of votes reported. She has a lead of 5 points.
• California's 27th: Democrat George Whitesides is challenging incumbent Republican Congressman Mike Garcia. With 67% of votes counted, Garcia leads by a narrow margin 2.4 points.
• California's 41st: Incumbent Republican Congressman Ken Calvert is running against Democrat Will Rollins. Calvert is winning by a narrow margin of 1 point with 60% of votes counted.
• California's 22nd: Democrat Rudy Salas is challenging incumbent Republican Congressman David Valadao, who currently leads with a margin of 10 points. A little over 50% of votes have been counted.
• California's 13th: Incumbent Republican Congressman John Duarte is running against Democrat Adam Gray. With 48% of votes counted, Duarte is leading by nearly 3 points.

The two closely watched races in the state currently have margins of less than 2%.

Republican Juan Ciscomani currently leads his Democratic challenger, Kirsten Engel, by 1.5 points in Arizona's 6th district located in the southeast corner of the state. About 60% of votes have been counted.

In Arizona's 1st district, David Schweikert has a lead of 1.6 points over Democratic challenger Amish Shah, with 62% of votes counted.

Schweikert's district covers north-eastern Maricopa County, outside of Phoenix.

In Maine, incumbent Democratic Congressman Jared Golden is fighting to keep his seat - one of two congressional districts in the state.

Maine's 2nd Congressional district encompasses the majority of the state north of Augusta and Portland.

Golden is currently leading in the race against his Republican challenger, Austin Theriault, by nearly 4 points. Around 77% of votes have been counted.

Democrats are looking to hold onto one seat in Ohio's 9th congressional district, which encompasses Toledo in northern Ohio.

Incumbent Democratic Congresswoman Marcy Kaptur, who has served in Congress since 1983, leads in the race against her Republican challenger, Derek Merrin.

Kaptur has a narrow 0.3 point lead. Around 94% of votes have been counted.