The race hasn’t been without drama: Lesko has been accused of violating campaign-finance law by moving $50,000 from her state Senate campaign to a federal political-action committee supporting her House bid. And in recent weeks, Tipirneni has been fending off attacks for wearing scrubs in her campaign videos, despite having been out of medical practice for more than a decade.

Two recent public polls show the race in a statistical dead heat, while a third shows Lesko with a lead of about 10 percentage points—still a far narrower gap than Republicans in the area are used to. And they’re clearly not willing to take any chances: Groups like the Republican National Committee, the National Republican Congressional Committee, and the Congressional Leadership Fund have so far poured roughly $1 million into the race. Lesko herself recently acknowledged the tightness of the race, saying in an interview, “Not only do I want to win, but I do want to win by a lot so we can show the Democrats that they don’t have a chance here.”

Mike Noble, a Republican pollster at OH Predictive Insights, the polling firm that predicted a 10-point victory for Lesko, is confident that an upset won’t happen. “This district is one of the safest GOP districts in the country,” Noble said. “This race will be closer than it is historically, but this is a Republican win at the end of the day.” Why? “Frankly, there’s too many Republicans,” Noble said, noting that they significantly outnumber registered Democrats in the district. Plus, Arizona’s 8th district is home to Sun City, known as the country’s original retirement community, which boasts a population of more than 37,000 residents and eight golf courses. (Lesko endeared herself to this particular community back in 2014 when she sponsored legislation legalizing golf carts for street use).

Another reason for Republicans to feel confident is that almost 140,000 voters—nearly two-thirds of the expected total—have already mailed in ballots, and most of those were from registered Republicans. The median voter age so far is 68.

Tuesday’s special election is happening just over a month after 33-year-old political newbie Conor Lamb eked out a win over Republican state Representative Rick Saccone in a Pennsylvania district that went for Trump by 20 percentage points in 2016. But comparing the two races is unwise, The Cook Political Report’s Dave Wasserman told me via email, because Arizona’s 8th district simply doesn’t have the same “Democratic heritage.” Democrats had a voter-registration advantage in the Pennsylvania district, as well as a large union presence, while “the leading demographic in AZ-08 is retired Fox News watchers.”

Still, Wasserman noted, if Tipirneni is able to get 45 or 46 percent of the vote on Tuesday, “that’s a really strong over-performance for Dems.” That this seems achievable is further evidence to both Democrats and Republicans that a blue wave, in some form or another, is coming in November. Most of that, Noble explained, has to do with Trump’s popularity. “If you have an ‘R’ next to your name, you are directly tied to President Trump,” Noble said, explaining that local independents are voting more in line with Democrats in order to oppose Trump—and it’s likely that fewer Republicans will vote out of indifference toward him. “That adds up to not a great year for the GOP.”