WASHINGTON – House Democrats released text messages Thursday evening that further fueled speculation over how the White House dangled military aid and a meeting with President Donald Trump as part of an effort to get Ukraine to investigate political rival Joe Biden.

The messages between Trump's then-special envoy to Ukraine, Kurt Volker, and other U.S. diplomats were sent before and after Trump asked Ukrainian President Volodymyr Zelensky in a July 25 phone call for "a favor" to investigate Biden and his son, Hunter, on charges of corruption.

The White House's release last week of a summary of the call prompted House Speaker Nancy Pelosi, D-Calif., to launch an impeachment inquiry into whether the president improperly used the resources of the U.S. government to pressure an ally for help in the 2020 campaign.

House Democrats released the text messages after Volker, who resigned from the Ukraine envoy post last week, spent more than nine hours Thursday testifying behind closed-doors as part of the Democrats' impeachment inquiry. They said the messages prove "stunning abuses" of power.

House Republicans argued the texts were a "unilateral and cherry-picked release" by Democrats and called for the full release of the transcript of Volker's interview.

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Here's a breakdown of some of the most important messages that Democrats released. The texts are verbatim. ("Potus" refers to President of the United States):

July 19:

Volker and Gordon Sondland, U.S. ambassador to the European Union, discuss goals for the upcoming July 25 call between Zelensky and Trump and refer to Bill Taylor, the top American diplomat in Ukraine.

Volker: Can we three do a call tomorrow – say noon WASHINGTON? Sondland: Looks like Potus call tomorrow. I spike [sic] directly to Zelensky and gave him a full briefing. He's got it. Sondland: Sure! Volker: Good. Had breakfast with Rudy this morning – teeing up call w Yermak Monday. Must have helped. Most impt is for Zelensky to say that he will help investigation – and address any specific personnel issues – if there are any

July 21:

Taylor relays concerns from the Ukrainian government:

Taylor: Gordon, one thing Kurt and I talked about yesterday was Sasha Danyliuk's point that President Zelenskyy is sensitive about Ukraine being taken seriously, not merely as an instrument in Washington domestic, reelection politics. Sondland: Absolutely, but we need to get the conversation started and the relationship built, irrespective of the pretext. I am worried about the alternative.

July 25:

Right before the call between Trump and Zelensky, Volker texts Andrey Yermak, advisor to Zelensky about expectations:

Volker: Good lunch - thanks. Heard from White House – assuming President Z convinces trump he will investigate / "get to the bottom of what happened" in 2016, we will nail down date for visit to Washington. Good luck! See you tomorrow- kurt

More:A visual timeline of the events that led up to Trump's fateful phone call

Aug. 10:

Yermak and Volker discuss terms of Zelensky's visit to the White House and what he's willing to say. Burisma is the Ukrainian energy company whose board included Hunter Biden.

Yermak: Hi Kurt. Please let me know when you can talk. I think it's possible to make this declaration and mention all these things. Which we discussed yesterday. But it will be logic to do after we receive a confirmation of date. We inform about date of visit and about our expectations and our guarantees for future visit. Let discuss it Volker: Ok! It's late for you – why don't we talk in my morning, your afternoon tomorrow? Say 10am/5pm? Volker: I agree with your approach. Let's iron out statement and use that to get date and then PreZ can go forward with it? Yermak: Ok Volker: Great. Gordon is available to join as well Yermak: Excellent Yermak: Once we have a date, will call for a press briefing, announcing upcoming visit and outlining vision for the reboot of US-UKRAINE relationship, including among other things Burisma and election meddling in investigations Volker: Sounds great!

Sept. 1:

Taylor seeks clarification for conditions of a White House visit.

Taylor: Are we now saying that security assistance and WH meeting are conditioned on investigations? Sondland: Call me

Sept. 9

Taylor and Sondland discuss the "hold" of military aid for Ukraine

Taylor: The message to the Ukrainians (and Russians) we send with the decision on security assistance is key. With the hold, we have already shaken their faith in us. Thus my nightmare scenario. Taylor: Counting on you to be right about this interview, Gordon Sondland: Bill, I never said I was "right". I said we are where we are and believe we have identified the best pathway forward. Lets hope it works. Taylor: As I said on the phone, I think it's crazy to withhold security assistance for help with a political campaign. Sondland: Bill, I believe you are incorrect about President Trump's intentions. The President has been crystal clear no quid pro quo's of any kind. The President is trying to evaluate whether Ukraine is truly going to adopt the transparency and reforms that President Zelensky promised during his campaign I suggest we stop the back and forth by text If you still have concerns I recommend you give Lisa Kenna or S a call to discuss them directly. Thanks.

Contributing: Deirdre Shesgreen, Kristine Phillips