The U.S. House of Representatives will vote Thursday to formalize the impeachment inquiry into President Donald Trump. In doing so, the House will officially acknowledge what no clear-eyed assessment can deny — that there is clear and mounting evidence that the president of the United States used the power of his office for personal gain, placing the smearing of a political rival over the country’s national security interests and those of our allies.

Since the public first learned of the allegations regarding Ukraine just last month, the picture has only worsened for the president. Credible witnesses have offered damning testimony, forcing the president’s allies to slink from one defense to another, resorting to stunts, spin and obstruction because it’s all they have left.

The need to continue with a full, unobstructed impeachment inquiry could not be more clear.

DAMNING TESTIMONY

Let’s start with the abridged transcript of the July 25 call between Trump and Ukraine President Volodymyr Zelensky, released by the White House itself. It shows Trump — after he has reminded Zelensky how much Ukraine needs U.S. support, and after Zelensky has asked for military aid — pressing the Ukrainian president to investigate (unsubstantiated) allegations against Joe Biden’s son as well as a (frankly bonkers) conspiracy theory on Ukrainian interference in the 2016 election.

Though he came close in the phone call, by that point Trump did not have to explicitly state what was at stake. The president’s personal attorney, Rudy Giuliani, had for months been pressing Ukraine for information favorable to Trump’s political prospects, often under the guise of pursuing a broader crackdown on “corruption” but always focused specifically on Biden’s son and the 2016 election.

And by the time of the phone call, nearly $400 million in aid already approved by Congress was being withheld from Ukraine, which desperately needed the funding in its war against Russian-backed separatists.

At the same time, Gordon Sondland, the ambassador to the European Union and major Trump donor who was pulled into Giuliani’s orbit, was pressing Ukraine to commit to those specific investigations in order to secure a much-desired meeting with President Trump, according to testimony Tuesday from Lt. Col. Alexander Vindman, a decorated Iraq War veteran.

Around this time, too, William Taylor Jr., acting ambassador to Ukraine, began noticing a “highly irregular” channel from the president to Ukraine through Giuliani, one that bypassed diplomatic protocol — and which spooked even John Bolton, the president’s national security adviser at the time, who made sure White House lawyers knew he wasn’t involved.

Taylor watched Giuliani push Zelensky to publicly commit to the investigations. Later, Taylor was told by Sondland that “everything” — the meeting with Trump as well as the military aid — was dependent on the investigations.

NO GOOD DEFENSE

In the face of this testimony, the president’s allies have struggled to defend him, attacking the process instead. They say the whistle-blower’s account shouldn’t be trusted, although the White House’s own transcript largely confirms it.

They’ve attacked the inquiry’s closed-door hearings, too, though such private interviews were part of both the Nixon and Clinton impeachment hearings, as well as the Republican-led inquiry into the attack in Benghazi, Libya. In any case, Republicans have been present and allowed to question witnesses at each hearing.

Trump’s allies are screaming about process because the facts look so bad for him. They appear to show a president using foreign policy as leverage to smear his domestic political rival, in the process hurting an ally engaged in a life-or-death fight with one of our chief adversaries.

We may not have heard about it if it were not for the whistle-blower. Now, others are coming forward to testify. Some who could shed light on the events surrounding Ukraine are being blocked by the Trump administration.

An impeachment inquiry can get to the bottom of it. Americans deserve the full story.