The past month has been the worst stretch of time in Donald Trump's entire presidency.

In foreign policy, Trump has sparked bipartisan outrage by pulling US troops out of northeastern Syria, effectively abandoning US-allied Kurdish forces there.

On the domestic front, the president is besieged by a rapidly expanding congressional impeachment inquiry.

Trump officials are defying orders to stay silent, offering testimony in the impeachment inquiry.

Their revelations give a damning impression of a concerted effort to leverage US foreign policy in exchange for material that would personally benefit the president.

More whistleblowers are also coming out of the shadows, potentially bringing more trouble for the president.

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The past month has been the worst stretch of time in Donald Trump's entire presidency.

A little over a week ago, Trump abruptly decided to withdraw US forces from northeastern Syria. The move prompted bipartisan criticism in Washington, including rare blowback from congressional Republicans, who accused the president of effectively abandoning US-allied Kurdish forces to a Turkish military invasion.

The Kurds bore the brunt of the US-led campaign against the terrorist group ISIS, losing roughly 11,000 fighters, and Trump was promptly accused of betraying US allies. Meanwhile, Trump was warned by US lawmakers and former officials that his decision could catalyze the resurgence of ISIS and create a power vacuum that Russia would be happy to fill.

Turkey invaded Syria last Wednesday, and within a week the situation has spiraled into a humanitarian catastrophe that ISIS and Moscow have already exploited.

Read more: FBI officials were 'rattled' and 'blindsided' by Trump's call for Ukraine to manufacture dirt on Joe Biden

Beyond the criticism of Trump's Syria retreat in Congress, leaders in Europe have said the president has significantly undermined the US's credibility by leaving the Kurds to fend off the Turkish assault.

Trump officials come out of the woodwork, defying his orders to stonewall Congress

All this comes as the president is besieged on the domestic front by an escalating congressional impeachment inquiry examining whether Trump used his public office for private gain.

At the heart of the investigation is an unprecedented whistleblower complaint filed by a US intelligence official.

The controversy exploded in mid-September, when House Intelligence Committee Chairman Adam Schiff revealed the existence of the complaint to the public.

Specifically, the intelligence official alleged that Trump repeatedly pressured Ukrainian President Volodymyr Zelensky during a July 25 phone call to investigate corruption allegations against former Vice President Joe Biden and his son Hunter. Trump also asked Zelensky to help discredit the FBI's finding that Russia secretly worked to help elect Trump.

Beyond asking a foreign power for dirt against a political rival ahead of an election, Trump is battling allegations that he held up a nearly $400 million military-aid package to Ukraine days before the phone call to maintain leverage over Zelensky.

Read more: The floodgates are opening as Trump officials publicly defy his orders and more whistleblowers come out of the shadows

In the weeks since, Trump officials have come out of the woodwork — defying his and other top officials' orders to stay silent — to offer testimony in the impeachment inquiry.

Taken together, their revelations paint a damaging portrait of a concerted effort from the highest levels of the Trump administration to leverage US foreign policy in exchange for material that would personally benefit the president.

They also show how far Trump went to involve his personal lawyer Rudy Giuliani. Here are the highlights:

Kurt Volker, the former special representative for Ukraine, turned over explosive text messages to Congress that revealed how intricately senior US diplomats were involved in Giuliani's efforts to dig up dirt on the Bidens.

The texts showed that Volker and another diplomat conveyed to Ukraine that a good relationship was predicated on the Ukrainian government's ability to pursue "investigations" and "get to the bottom" of what happened in 2016.

The second diplomat, Gordon Sondland, the US ambassador to the European Union, is expected to testify to Congress this week that the content of a text message he wrote denying there was a quid pro quo exchange with Ukraine was relayed to him directly by Trump.

Sondland is reportedly expected to go even further and tell lawmakers he doesn't even know if Trump was being honest when he denied the quid pro quo.

Marie Yovanovitch, a former US ambassador to Ukraine who refused to go along with Trump's and Giuliani's efforts against Biden, testified that she was abruptly recalled in May based on "unfounded and false claims by people with clearly questionable motives."

Yovanovitch said she was removed despite the State Department's belief that she had "done nothing wrong." She also said there had been "a concerted campaign" against her and that the department "had been under pressure from the president to remove me since the summer of 2018."

Fiona Hill, the White House's former top Russia analyst, testified that John Bolton, the former national security adviser, was so angry with the pressure campaign on Ukraine that he instructed her to tell White House lawyers about it.

Hill also said Bolton described Giuliani as a "hand grenade" who would "blow everybody up." She added that she witnessed "wrongdoing" while serving in the Trump administration.

Read more: These are the key players you need to know to make sense of the Trump impeachment inquiry

More whistleblowers come forward as Giuliani faces a federal criminal probe

Meanwhile, the president could face even more whistleblowers as other government officials consider stepping forward.

The attorneys representing the first Ukraine whistleblower have said they're representing a second US intelligence official who has more information about Trump's call with Zelensky.

And the House Ways and Means Committee is trying to learn more about a third whistleblower, who works in the IRS and whose complaint alleges "inappropriate efforts to influence" the agency's audit of Trump's tax returns, a court filing from the committee said.

According to The Washington Post, the person accused of trying to interfere with the audit is a political appointee at the Treasury Department.

Citing two congressional sources, The Daily Beast reported last week that new potential whistleblowers were coming forward in the wake of the House's impeachment inquiry.

Amid the firestorm, Trump has resisted calls to beef up his legal team and White House war room.

But the president may well have to look elsewhere soon, given that Giuliani is at the center of a broadening federal criminal investigation into whether he broke foreign lobbying laws while working to oust Yovanovitch.