The diplomatic texts released by Congress overnight do not leave much doubt about the quid pro quo being offered to Ukraine. They also say a lot about how far the state department has been warped by the Trump administration.

The transformation is made clear by the three protagonists. Bill Taylor is on his second stint as ambassador to Ukraine, this time in an acting capacity because Donald Trump abruptly fired his predecessor in May. He is a 72-year-old Vietnam veteran with decades of experience.

Kurt Volker is another diplomatic veteran, a former ambassador to Nato who was until last week the administration’s special envoy on Ukraine.

The third man is Gordon Sondland, a wealthy hotelier who paid $1m to fund Trump’s inauguration and was then given the job of ambassador to the European Union last year. He has no previous diplomatic experience and Ukraine, not being a EU member, is not on his turf.

But it is clear from the texts that Sondland is in charge and driving the hard bargain with the Ukrainian president, Volodymyr Zelenskiy: do what we tell you or forget about a White House visit and a reboot of US-Ukrainian relations.

Sondland derives his authority by his connection to the White House – a power he repeatedly flaunts in his texts.

The institutional hierarchy of the state department carries no weight in these exchanges. The secretary of state, Mike Pompeo, is not even mentioned. We now know he listened to the fateful call between Trump and Zelenskiy, which is at the core of impeachment proceedings, but has since sought to keep his head down. He clearly did not obstruct the back-channel instructions coming from the White House, through Trump’s personal lawyer, Rudy Giuliani.

As the impeachment storm has broken over Washington, he has absented himself on a European tour, going to see the pope and visit the Pompeo ancestral home in Italy. That may provide useful show reel for a much-awaited Senate run in Kansas, but when it comes to the political arena in 2020 total loyalty to Trump may cut both ways.

Until last week Kurt Volker was the administration’s special envoy on Ukraine. Photograph: Zach Gibson/Getty Images

On Friday, the secretary of state was in Montenegro where he axed the question-and-answer part of his scheduled press conference.

Daniel Drezner, the professor of international politics at Tufts University, wrote in the Washington Post that Pompeo has “created a culture at state in which senior diplomats catered to every presidential whim regardless of its legality and morality”.

“As it turns out, Pompeo and decency do not mix. He needs to resign,” Drezner wrote.

The responses of Taylor and Volker say a lot about the everyday dilemmas many state department staff are having to contend with. They are well aware Pompeo is not going to defend them. He said nothing when Taylor’s predecessor in Kyiv was ousted on Trump’s instructions in May – and then smeared by the president and the far-right media.

Taylor tries to resist. Having been brought back from retirement already he has little to lose. And his resistance comes in the form of describing clearly, for the digital record, the shakedown that Zelenskiy is being subjected to.

“I think it’s crazy to withhold security assistance for help with a political campaign,” he texted to Sondland.

By the time of that text, 9 September, the White House was already well aware its dealings with Zelenskiy were coming under official scrutiny. Sondland suggests they discuss the matter offline.

Volker is a much more eager participant that Taylor – to the surprise of former colleagues who had predicted that he would have kept his involvement in the political bargaining to a minimum.

In the exchanges with Sondland and Giuliani he is enthusiastic about the venture and goes as far as drafting a statement for Zelenskiy to read out, explaining how he is going to investigate Hunter Biden’s company and Ukraine’s (non-existent) role in the 2016 US election.

Volker emerges as a somewhat tragic figure. When he went into the part-time Ukraine job he commanded bipartisan respect, frequently described as “a straight arrow”. His friends argue that he would have seen dealing with Giuliani and Sondland as the price that had to be paid for the greater good, which was maintaining the Washington-Kyiv relationship and thereby shoring up Ukrainian independence in the face of Russian aggression.

His resignation and full cooperation with Congress suggest he is aware he went too far seeking to appease Trump. Few come away unsullied from dealings with this White House.

The damage is not just personal but institutional. It is clear from the texts that loyalty to Trump is far more important than official US policy or institution norms. Sondland was in charge – in a country he knew nothing about.

“What on earth is he doing on this? He has been taken from the EU and put on this clearly as the ringmaster,” Thomas Wright, the director of the centre on the US and Europe at the Brookings Institution, said. “He is there as the personal representative of the person … He is there as the person who is trusted to make sure this gets done.”

“It’s pretty clear that Pompeo has allowed the state department to be used by Trump for his own political ends,” Wright added.

Richard Grenell, the US ambassador to Germany, was also dispatched to Kyiv.. On Friday he was given a second job, the special envoy for peace negotiations between Serbia and Kosovo.

Like Sondland, Grenell is an unquestioning Trump loyalist with little or no relevant experience in a tense and complicated part of the world, where there are particularly high stakes. And like Ukraine, the countries of the former Yugoslavia are of special interest to Vladimir Putin.