Sen. Susan Collins, R-Maine, refused to endorse President Donald Trump for re-election on Tuesday, part of a pattern of the past two years in which she downplays her support for Trump, expresses deep reservations about his presidency then, ultimately, pushes his agenda through.

Days after the Republican National Committee pledged to give Trump unprecedented support heading into the 2020 election, Collins told “PBS NewsHour” she hadn’t decided whether she would support Trump.

“I’m really focused on my own campaign for 2020, and I really haven’t focused on the presidential campaign, so I’m not prepared at this point to make that decision,” Collins said. “I’m going to have to see what happens between now and then and look at what his record is.”

But Collins, who is running for a fifth term in a state Trump lost in 2016, has voted with Trump 94 percent of the time, a 17-point increase from her support for the last Republican president she served with, George W. Bush, according to a CQ analysis.

While Collins voted with Bush 76 percent of the time during his two terms, that number fell to just 59 percent in 2008, a year she faced re-election and his poll numbers were plummeting.

Her votes in the Senate have proved key to some of Trump’s biggest legislative achievements: the tax bill that provided a windfall for the wealthy and corporations and the confirmations of Jeff Sessions as attorney general and Brett Kavanaugh as a Supreme Court justice.

The tax bill, ironically, eliminated the individual mandate in the Affordable Care Act, creating the possibility that coverage under the ACA, which Collins voted to protect months earlier, would be wiped out.

Collins told “PBS NewsHour” on Tuesday she likely wouldn’t endorse any Democrat currently running but didn’t rule out endorsing a different Republican, should one challenge Trump.

Months before the 2016 election, Collins denounced Trump and declared she wouldn’t support him.

“I will not be voting for Donald Trump for president,” she wrote in The Washington Post. “This is not a decision I make lightly, for I am a lifelong Republican. But Donald Trump does not reflect historical Republican values nor the inclusive approach to governing that is critical to healing the divisions in our country.”

Still, she effectively sat out the presidential campaign by refusing to support his Democratic opponent, Hillary Clinton.

Collins has publicly agonized over several decisions during the Trump administration but has more often than not sided with Trump and her party.

In October, Trump singled out Collins for praise after she announced she would vote to confirm Kavanaugh despite testimony that he attempted to rape a woman in high school.

“I want to also thank you for some of the most beautiful words,” Trump said, referring to her announcement. “It was incredible. Admired by everybody. Thank you, Susan. Really amazing. Thank you very much.”