We’ve come a long way if we now think of former President George W. Bush and his advisors as rational Republicans.  But in a season that has seen once-respected GOP leaders obsequiously genuflect before President Donald Trump, Bush–who says he left his presidential ballot blank in 2016–appears to be emerging as a firm voice against the current president. It’s an unlikely development–but, perhaps, a crucial one.

Speaking in Abu Dhabi today, Bush said “there’s pretty clear evidence that the Russians meddled” in the 2016 election, pointedly contradicting the White House line that no interference occurred. Furthermore, Bush spoke in favor of a strong NATO alliance to check Russia’s Vladimir Putin, whom the former president described as having a chip on his shoulder.

Bush also waded into the contentious immigration debate, deviating from the White House’s hard-line position. “There are people willing to do jobs that Americans won’t do,” Bush said. “We ought to say thank you and welcome them.”

Bush’s statements alone represent a prominent rebuttal to the current administration. But they come at a moment when several members of Bush’s political orbit also are speaking out against Trump, even as Congressional leaders like House speaker Paul Ryan fall deeper into the president’s gold-plated thrall.

On Monday, former Bush speechwriter Michael Gerson published a scathing op-ed in the Washington Post, lambasting party leaders–Ryan, in particular–for parroting Trump’s attacks on the FBI, the national intelligence community, and basic Constitutional checks and balances. “Trump has made a practice of forcing people around him to lower their standards and abandon their ideals before turning against them when their usefulness ends,” Gerson writes. “A generation of Republicans will end up writing memoirs of apology and regret.”

For good measure, Gerson added: “This is a rare case when the rats, rather than deserting a sinking ship, seemed determined to ride it all the way down.”

That Gerson, the author of such controversial neocon neologisms as “the Axis of Evil” and “we don’t want the smoking gun to be the mushroom cloud,” should inveigh against the Trump administration in terms as strident as, say, Nancy Pelosi or Elizabeth Warren is a fairly stunning development.

And he’s not alone. His fellow Bush speechwriter David Frum has been an outspoken critic of Trump. And former State Department official Lawrence Wilkerson, who helped craft Colin Powell’s infamous “yellow-cake uranium” presentation at the United Nations, also spoke out against the Trump administration this week, in his case asserting that the administration is on a reckless crusade to start a war with Iran. “We’ve seen this before: a campaign built on the politicization of intelligence and shortsighted policy decisions to make the case for war. And the American people have apparently become so accustomed to executive branch warmongering — approved almost unanimously by the Congress — that such actions are not significantly contested,” Wilkerson wrote in the New York Times.

Republicans in Congress may continue to tap dance for Trump, but Bush & friends clearly feel no compunction to do so. 43 will forever be judged for the grave policy decisions he made as president. But if he’s able to use his stature now to animate Republican critics of the Trump presidency–and thereby safeguard fundamental American values–he may yet pay off the debt that many feel he owes us.