(CNN) - Democrat Kyrsten Sinema has defeated Republican Vernon Parker in the race for Arizona's 9th Congressional District, CNN projected Monday.
Sinema's win in the newly-created district adds one more seat to the list of pick-ups for Democrats in the House, putting the breakdown at 234 Republicans, 196 Democrats and two independents.
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Including Sinema's win in Arizona, Democrats have gained a net of three seats in the House this cycle.
Sinema, a former state senator, had 48.1% of the vote compared to Parker, the former mayor of Paradise Valley, at 45.3%, according to the office of Arizona's Secretary of State on Monday.
Both parties had invested heavily in the race, though a Democratic super PAC had tipped the TV ad war balance of power slightly in the Democrat's favor.
Five races remain too close to call from last week's elections, including contests in Arizona, Florida, North Carolina and two races in California.
While Democrats have an edge in all five, a sixth unresolved House race will be settled in a December 8 run-off between two Republican incumbents, guaranteeing a GOP seat.
– CNN's Robert Yoon and Adam Levy contributed to this report.