Democrats are hoping that U.S. Ambassador to the European Union Gordon Sondland will be their breakthrough witness, with polls showing that most Americans are not paying close attention to the impeachment hearings.

Democrats accused Sondland of being part of the “irregular channel” of U.S. policymaking on Ukraine that, they allege, President Donald Trump used to pressure Ukraine into investigating his political rivals.

Sondland has testified that he worked with other officials — mostly former Ambassador Kurt Volker and Secretary of Energy Rick Perry — to convince the Ukrainian president to issue a statement committing to investigations of allegations of Ukrainian interference in the 2016 presidential elections, and an investigation into Burisma, a Ukrainian natural gas company whose CEO was under investigation for corruption.

Sondland has testified that the president’s personal lawyer, former New York City Mayor Rudy Giuliani had pushed for the statement, presumably on Trump’s behalf.

But Sondland has also testified that he has never known of any “quid pro quo” — and that President Trump told him directly that he wanted “nothing” from Ukraine.

He later amended his testimony to say that he remembered he had a conversation with a Ukrainian official linking withheld military aid to the statement on the investigations, but he also testified that by that late stage in the process,  he just “presumed” that was the case but did not know personally.

Key Democratic Talking Points:

1. Democrats are hoping to use Sondland — who claimed to have direct access to Trump — to link the president directly to a “quid pro quo,” trading a White House meeting or military aid for politically helpful investigations.

2. Democrats plan to grill Sondland about the closed-door testimony of David Holmes, who has alleged that he overheard Sondland speaking directly to the president on July 26, a day after Trump’s phone call with Ukrainian President Volodymyr Zelensky. Holmes allegedly could hear Trump say “the investigations,” and also said Sondland told him afterwards that Trump cared “more about the investigations” than he did about Ukraine.

3. Democrats will argue that Sondland had no business working on Ukraine policy since he was the U.S. ambassador to the EU. They will argue that the “irregular channel” was meant to bypass the “regular channel” that involved U.S. diplomats at the embassy in Kiev, and the National Security Council. Democrats will also try to attack Sondland’s past experience as a businessman and a donor to the Trump campaign.

Follow Breitbart News’ @Kristina_Wong.