"Arizona is the place where the battle is going to happen, because the president cannot be reelected without winning both Arizona and Pennsylvania," Luntz said on "Squawk Box."
Biden currently has 253 of the 270 electoral votes needed to win the presidency, according to NBC News. Trump has 214. In addition to Arizona, the presidential contests have not been called by NBC News in Nevada, Georgia, Pennsylvania, North Carolina and Alaska. All together, there are 71 electoral votes that are unclaimed, according to NBC News.
Luntz said he believes Arizona is critical to Trump's fortunes due to his personal outlook on the race in Nevada, which has six electoral votes. NBC News considers the contest too close to call, with 86% of the expected vote in. Biden has 49.3% compared with Trump's 48.7%, per NBC News.
"I believe Nevada, when all the votes are counted, stays in Biden's camp," Luntz said. "There are too many votes that are missing there from Las Vegas, and not enough missing from the rest of the state, which is more likely to vote Republican than Vegas is."
However, Luntz said he was not yet writing off Arizona as election officials in the state continue to tabulate votes. There are nearly 500,000 votes yet to be tallied, according to NBC News. "Arizona can flip to Trump, based on where the votes are still coming from," Luntz said.
On Wednesday, the presidential contests in Wisconsin and Michigan were called in favor of Biden, according to NBC News. Wisconsin has 10 electoral votes, while Michigan has 16.
Pennsylvania's race is too close to call, with 89% of the expected vote in, according to NBC News. Trump leads in the Keystone State with 50.7% of the vote, compared with Biden's 48.1%.
A victory alone in Pennsylvania, which has 20 electoral votes, would put Biden over the key 270 threshold. Another path to victory for Biden includes winning Arizona and Nevada.
While Luntz said he believes Trump will prevail in North Carolina and Georgia, he said he likes Biden's chances to win Pennsylvania, and by extension the overall race, as the additional mail-in votes are counted. "Based on the fact that so many of them are coming from Philadelphia or the Philadelphia suburbs, which is so strongly Democratic at this point, ... I think that it does flip to Joe Biden," Luntz said.
With his path to 270 narrowing, Trump's campaign is pursuing legal action in Pennsylvania, Michigan and Georgia pertaining to vote counting. The Trump campaign also wants a recount in Wisconsin, which has already been called by NBC News for Biden.