***UPDATE: U.S. Rep. Tom O’Halleran on Sept. 26 announced his support for the impeachment inquiry.

In the face of Donald Trump’s attempt to put American citizens in the legal crosshairs of a foreign country for his political gain and then violate federal law by refusing to turn over a whistleblower complaint to Congress – by far his most brazen abuse of power among the long list of them in less than three years – Arizona Democrats have all concluded that the best, and perhaps only, response from Congress at this point is to impeach the president.

All, that is, except one: Tom O’Halleran.

This is a scandal that has evolved rapidly since The Washington Post first reported Sept. 19 that Trump’s communications with a foreign leader were the subject of the whistleblower complaint from a member of the intelligence community. That complaint was reviewed by intelligence community Inspector General Michael Atkinson (a Trump appointee), who determined it was both credible and of “urgent concern,” triggering a provision in the law requiring its disclosure to Congress.

The Trump administration has since stonewalled and refuses to turn over the complaint, citing “privileged communications,” despite no provision in the law allowing for any exemptions or privilege.

Fast-forward to today, and we now know that Trump, in a July 25 phone call with Ukrainian President Volodymyr Zelensky, repeatedly said he wanted Ukraine to investigate his chief political rival – Joe Biden – and his son. The phone call came a week after Trump ordered the withholding of $400 million in congressionally appropriated funds to help Ukraine defend itself against Russia.

The allegations from Trump and his enablers are that Biden, when he was vice president in 2016, pressured Ukrainian officials to remove Prosecutor General Viktor Shokin from office, ostensibly to cut short an investigation into a gas company of which Biden’s son, Hunter, sat on the board.

The idea of a Biden conspiracy falls apart, however, under even the slightest examination. The probe into the company had long been dormant, and the prosecutor’s removal was called for by many Western leaders because he was failing to fight corruption. He was also the subject of a decisive vote of no confidence by Ukrainian lawmakers.

And the current prosecutor general for Ukraine says there is not a single piece of evidence that either Biden did anything illegal or corrupt.

All of which brings us back to O’Halleran, a Democrat from Sedona. After months of avoiding a growing swell in her caucus for impeachment, House Speaker Nancy Pelosi today said the U.S. House of Representatives will formally begin impeachment inquiry proceedings.

There are now nearly 180 House Democrats who support an impeachment inquiry, including 44 who have announced their support this week alone.

O’Halleran stands alone among Arizona’s five Democrats in refusing to engage the constitutional check on a president who so readily and flagrantly abuses his power.

His office today released a statement that studiously avoids the word “impeachment,” even in light of such a “shocking abuse of power” like Trump pressuring a foreign government into “digging up dirt on a political opponent.”

The proper response, O’Halleran says, is “a prompt and thorough investigation.” And if the Trump administration doesn’t cooperate and provide information to Congress, “then further action is warranted.”

If violating the intelligence community whistleblower law to keep the whistleblower report secret doesn’t warrant further action – this, on top of Trump’s sweeping view of executive privilege, such that it covers anything and everything, including people who never worked in the administration – then I shudder to think what it would take to get O’Halleran to recognize the gravity of our present moment and the consequences that will come if Congress fails to do the job it is constitutionally required to do.