As Tuesday’s Arizona Senate primary nears, the three Republican candidates running to replace retiring Sen. Jeff Flake are working overtime to win a last-minute endorsement from President Trump.

In many GOP primaries, the president’s backing has been the golden ticket to help candidates win, and some believe it would seal the deal for frontrunner Rep. Martha McSally. To the frustration of many who want Trump to choose, however, neither McSally, Kelli Ward nor Joe Arpaio has received the coveted prized. Even so, each has claimed to be the truest supporter of Trump and labored to create the optics of an implied endorsement.

McSally touts pictures of herself in the Cabinet Room sitting near the president discussing immigration. She’s aired a television clip of Trump calling her the “real deal.” On Aug. 13, she went to an event in upstate New York where he signed a defense spending bill and gave McSally a glowing shout-out, saying that “she’s terrific.” McSally’s even been to movie night at the White House, giving her insider bragging status.

Still, despite racking up endorsements from former Gov. Jan Brewer, the important Arizona Republic, former House Speaker Newt Gingrich and the National Federation of Independent Business, McSally is eerily missing the one crucial endorsement in this race: President Trump’s.

Former state Sen. Kelli Ward has sent out a mailer using an edited year-old Trump tweet, which says, “Great to see that Kelli Ward is running.” However, most of the tweet was about how much he dislikes Flake, who is retiring in part due to his strained relationship with the president. Ward has even tried to elevate her Trump groupie status by having different life-sized cardboard cutouts of the president displayed at campaign events.

Arpaio, former Maricopa County sheriff and an immigration hard-liner, highlights that he was one of Trump’s first supporters and would be a die-hard fan in the Senate. The best proof of his close relationship with the president is that Trump pardoned Arpaio following a conviction for criminal contempt of court after he disobeyed a federal judge's order to stop racial profiling when detaining suspected illegal immigrants.

The RealClearPolitics polling average shows McSally with an eight percentage-point lead, but the latest public survey by Phoenix-based OH Predictive Insights puts her up by 20 points. She is the only candidate with enough money to keep running television ads up to the primary. However, the bitterness of the drawn-out expensive campaign and the relentless amounts of negative ads thrown at the frontrunner could be taking their toll. The Ward campaign claims to have internal polling showing her pulling even.

Further complicating McSally’s campaign is that she’s running as a moderate against two more conservative candidates, where any softness regarding support for Trump is perceived as damaging. An actual endorsement would clarify who is the Trumpiest candidate of them all.

The McSally camp is pushing the narrative that she’s the only candidate who can win the general election against Rep. Krysten Sinema and keep the seat in Republican hands. In an unusual move, some reports say both Majority Leader Mitch McConnell and Sen. Cory Gardner, head of the National Republican Senatorial Committee, have asked the president to weigh in for McSally. As one person from Team McSally put it: “The president could wrap this up with one tweet.”

In the meantime, outside groups and candidates have pumped nearly $7 million into the primary. Trump loyalists/mega-donors Bob and Rebekah Mercer have spent heavily on Ward’s behalf, trying to derail the McSally effort by claiming she’s a phony Trump supporter. On top of that, the Democratic super PAC Red and Gold has spent about $2 million on negative ads against McSally. This group has the double objective of defeating McSally in the primary, so Sinema has a weaker opponent, and, barring that, introducing negative messages about McSally that could color perceptions of her in the general election race.

Time is running out in the primary. It’s estimated that as much as 65 percent of the ballots have been cast through early voting, so the maximum effectiveness of a Trump endorsement is already diminished. The president in the last two days has tweeted out two more endorsements for midterm candidates in other races, but there’s been nothing yet regarding the Arizona Senate contest. As each day passes, it becomes more likely that Trump will not endorse anyone, leaving Republican voters to figure it out on their own.