"Today isn't a day for partisan politics," Masto said in the statement. "Today is a day to thank Senator Reid for his service to Nevada. I wish him all the best."
A Latina in a state where one-third of the population is Hispanic, Masto has a family name that goes way back in Nevada politics. Her father, Manny Cortez, who passed away in 2006, is credited with transforming the Las Vegas strip into the tourism destination it is today as longtime head of the Las Vegas Convention and Visitors Authority. He and Reid had a long-standing relationship, and Reid has known Cortez's daughter for years.
Masto's connection with Reid has led to controversy in the past. In 2008, her office indicted then-Lt. Gov. Brian Krolicki, a Republican who had started exploring a Senate run against Reid, on charges that a judge threw out a year later. But the indictment still derailed Krolicki's political plans, and he remains miffed that Masto never apologized. Reid went on to win reelection narrowly against a gaffe-prone opponent in 2010.
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Masto previously served as a prosecutor in the U.S. Attorney's Office in Washington, D.C., and as former Nevada Gov. Bob Miller's chief of staff. Democrats who have worked with Masto describe her as a hard worker but a less "bombastic" partisan than the average statewide candidate (or Reid, for that matter).
She has been talked about as a potential candidate for Senate or governor in the past; in particular, allies say her talks with Reid about the Senate go back years. But Masto took a pass on running for another office in 2014 to take a job with the Nevada System of Higher Education. In doing so, she avoided a historic Republican wave that left Reid as the only Democrat left in statewide office, keeping her record unblemished for a potential run this year.
"The Cortez family and the Reids have been very close," said Nevada Democratic strategist Andres Ramirez. "I think you're going to see Reid do a full-court press on her behalf. Having her background and Reid's infrastructure will certainly make for a much easier way to capture the election."
Republicans note that Masto's candidacy would have some question marks. She has "never been in a fight," said one Nevada Republican. But even he called Masto a "rock star on paper."
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"Harry Reid remains one of the most unpopular politicians in Nevada and his endorsement isn't something to brag about," National Republican Senatorial Committee spokesman Jahan Wilcox said of the minority leader's support for Masto. Other Republicans believe—or hope—that the political machine Reid built wouldn't run for anyone but him.
In addition to her relationship with Reid, Masto would come into the Senate race with built-in ties to national groups that support women and Hispanic candidates.