Democratic attorneys general from key states said they have not yet been invited by the Justice Department to its upcoming review of tech companies, prompting criticism that the Trump administration's inquiry is a politically charged attack on the tech industry.

U.S. Attorney General Jeff Sessions first announced on Wednesday that he was gathering state attorneys general to examine whether companies like Facebook, Google and Twitter are “intentionally stifling the free exchange of ideas” online. The goal of the meeting, the Justice Department said in a statement at the time, is to follow up on a hearing that had just taken place on Capitol Hill with Facebook and Twitter and consult with "a number" of states to figure out if Silicon Valley's conduct is "hurting competition." The meeting is tentatively scheduled for Sept. 25 in Washington.

Democratic attorneys general from California and New York — two tech hubs — as well as officials from Connecticut and Washington, which are active on issues related to technology, consumer protection and antitrust, so far have not been invited, representatives for each state confirmed this week.

The Democratic Attorneys General Association said it "had not heard any Democratic attorneys general [are] invited" as of Friday morning, according to communications director Lizzie Ulmer.

Only Ken Paxton, the Republican attorney general of Texas, has said he will participate at the event, slated for later this month, a spokesman said.

The Justice Department has received inquiries from a number of Republican and Democratic attorneys general, according to a person familiar with the planning, who said planning for the meeting is still in its early stages.

A spokesman for the Justice Department declined to comment.

The potentially partisan nature of DOJ's meeting raised deep suspicions among some tech experts, particularly against the backdrop of President Trump's recent comments attacking social media sites as biased against conservatives — and threatening regulations and investigations in response.

"This type of meeting, in a highly politically charged environment, will have no credibility if all the participants come from the same political party," said Gene Kimmelman, a former top official at the Justice Department who is now the president of Public Knowledge, a consumer group.

The Washington Post this week reached out to all 50 states' attorneys general. By Friday, 10 Democrats and five Republican state attorneys general said they had not received an invitation. The lack of clarity led Bob Ferguson, the attorney general of Washington state, to write Sessions on Friday to ask him to explain who was invited, why they were invited and if Trump’s tweets last week accusing tech companies of ideological bias played a role in Sessions’s announcement. The Justice Department was working on the issue before lawmakers convened their hearing Wednesday, according to a person familiar with the plans who was not authorized to speak publicly.

“Normally, you’d want to invite all the state AGs because you don’t want to leave uncoordinated some of those relationships,” said Jeffrey Blumenfeld, a former DOJ antitrust official and a partner at the law firm Lowenstein Sandler. “I don’t know of a time, ever, where there was picking and choosing among state AG offices at the invitation level.”