Senator Catherine Cortez Masto managed to hang on to her seat in a close race that nearly saw her beaten by her Republican adversary, with the result leaving control of the US Senate in the hands of Democrats.

After Democratic senator Mark Kelly’s victory in Arizona on Friday, the party now holds a 50-49 edge in the Senate. The Democratic party will retain control of the chamber, no matter how next month’s Georgia runoff plays out, by virtue of vice-president Kamala Harris’ tie-breaking vote.

Cortez Masto, America’s first Latina senator, beat out Adam Laxalt, a former Nevada attorney general who aided in efforts to overturn the results of the 2020 election, according to the Associated Press.

The race was among the tightest in the country and saw record spending with $158m on TV ads, $15m raised for Laxalt and $52m for Cortez Masto. The contest was crucial for Democrats to maintain control of the Senate, along with races in Pennsylvania and Arizona Democrat wins.

Nevada’s vote count took several days partly because of the mail voting system created by the state Legislature in 2020 that requires counties to accept ballots postmarked by election day if they arrive up to four days later. Laxalt had an early lead that dwindled after late-counted ballots came in from the state’s population centers in Las Vegas and Reno.

High-profile Democrats had joined efforts to re-elect Cortez Masto in recent days, with Bill Clinton and Barack Obama making appearances with the senator. Cortez Masto also had the backing of 14 members of Laxalt’s family, who said she “possesses a set of qualities that clearly speak of what we like to call ‘Nevada grit’”.

Democrats had dialed up efforts to reach voters with the state party contacting thousands of voters, and the local culinary union – which backed Democratic candidates – knocking on 1m doors in the state of 3 million people.

Associated Press contributed to this report