UPDATE: As expected, Palin officially endorsed Trump. Touting the endorsement, Trump said in a statement, “I am greatly honored to receive Sarah's endorsement,” adding, “She is a friend, and a high-quality person whom I have great respect for. I am proud to have her support.”

ORIGINAL POST: Numerous media outlets have speculated that Sarah Palin will endorse Donald Trump for president at an Iowa rally tonight. Over the years, Palin and Trump have cultivated a mutual admiration society, complimenting and supporting each other.

The day after the 2008 election, Trump told Fox News' Greta Van Susteren that despite her failure to be elected vice president, Palin was a “fine woman” who “made things interesting.”

The two crossed paths in 2011 when Trump was again promoting the birther conspiracy theory about President Obama's place of birth. Palin defended Trump, telling Greta Van Susteren that “I respect what he's doing in putting his money where his mouth is. He's actually investigating his speculation there on Obama's birth certificate and Obama's college records and all those things that Obama, though he promises to be a transparent official, he certainly isn't because he could certainly reveal many of these documents and put many of these issues to rest.” In another Fox interview Palin praised the birther push, saying “more power to him.”

Trump later expressed his appreciation for Palin's support in a Wall Street Journal interview, noting she was “so gracious to me on the birther issue.” (Think Progress has explained how the pair have “bonded over birtherism.”)

Later that year when Palin went on a multi-city bus tour as speculation built that she might announce a presidential run in 2012, one of her most-covered stops was in New York City where she had pizza with Trump.

At the time there were questions about whether Palin might choose Trump as her running mate. Trump said, “She didn't ask me, but I'll tell you, she's a terrific woman.”

After Trump officially announced his presidential run in 2015, Palin has been a reliable source of support for him.

On Breitbart.com, Palin wrote an op-ed praising Trump, writing that “The elites are shocked by Trump's dominance, but everyday Americans aren't.”

Palin guest hosted an episode of the conservative One America News Network's program On Point and interviewed Trump. She sympathized with him over “personal 'gotcha' questions” which were “really trying to get you, us, anybody running for office off game.”

Responding to Trump's statement that he'd “love” for Palin to serve in a Trump administration, she floated her name for secretary of energy. She told CNN's Jake Tapper, “I think a lot about the Department of Energy, because energy is my baby: oil and gas and minerals, those things that God has dumped on this part of the Earth for mankind's use instead of us relying on unfriendly foreign nations.”

When Trump was criticized after he disparaged the military service of former Palin running mate Sen. John McCain (R-AZ), Palin called both McCain and Trump heroes and said, “Trump is the candidate giving voice to untold millions of fed-up Americans witnessing a purposeful destruction of our economy and the equal opportunity for success that made America exceptional.”

Trump called in to a pro-Palin internet radio show, “The Palin Update,” on Mama Grizzly Radio and told listeners that voters have been asking him when he would get her support, “I still have people saying, 'Get Sarah's support! Get Sarah's support!' No matter where I go.”

Palin also had Trump's back after he fumbled over a series of foreign policy questions with conservative radio host Hugh Hewitt. She said, “I think I'd rather have a president who is tough and puts America first than can win a game of Trivial Pursuit.”

In another sign of their philosophical alignment, Trump recently hired the former chief of staff of Palin's PAC to be the national political director for his campaign.