The House select committee investigating the Capitol attack on Thursday subpoenaed Trump operative Phil Waldron, the retired colonel whose PowerPoint recommending Donald Trump declare a national emergency to return himself to office was sent to the White House chief of staff.

The subpoena to Waldron, demanding documents and testimony, marks the select committee’s focus on the PowerPoint and the extent that the document’s recommendations – as reported by the Guardian – were considered by the White House or the former president himself.

Bennie Thompson, the chairman of the select committee, said in the subpoena letter he wanted to depose Waldron as part of their inquiry into the 6 January insurrection and determine the precise nature of his repeated contacts with Trump’s former chief of staff Mark Meadows.

Thompson said the select committee was pursuing Waldron’s cooperation to also establish the nature of his visits to the White House, his briefings to members of Congress, and his participation in meetings held at the Willard hotel in Washington DC just before 6 January.

“The document he reportedly provided to Administration officials and Members of Congress is an alarming blueprint for overturning a nationwide election,” Thompson said of the PowerPoint. “The Select Committee needs to hear from him.”

The select committee subpoenaed Waldron after he emerged as an author of the PowerPoint titled “Election Fraud, Foreign Interference & Options for 6 Jan”, which ended up in Meadows’ personal email inbox – and he met with Meadows repeatedly before the Capitol attack.

The PowerPoint recommended in brazen terms that Trump declare a national security emergency on the basis of lies about election fraud, and that then-vice president Mike Pence abuse his ceremonial role to stop Biden’s certification on 6 January, the Guardian first reported.

The fact that Meadows was in possession of a PowerPoint that outlined steps to stage a coup, and met with its lead author almost a dozen times before the Capitol attack, is significant as it suggests the Trump White House knew of plans to stop Joe Biden’s certification.

Senators and members of Congress should first be briefed about foreign interference, the PowerPoint said, at which point Trump could declare a national emergency, declare all electronic voting invalid, and ask Congress to agree on a constitutionally acceptable remedy.

The PowerPoint also outlined three options for then vice-president Mike Pence to abuse his largely ceremonial role at the joint session of Congress on 6 January, when Biden was to be certified president, and unilaterally return Trump to the White House.

In a letter to Meadows’ attorney, George Terwilliger, the select committee noted that among the 6,000 documents Meadows produced was an email accompanying the PowerPoint that indicated it was to be “presented on the Hill”, a reference to Congress.

The contents of the PowerPoint was ultimately briefed to a number of Republican members of Congress on 4 January, according to a source familiar with the matter. The Washington Post reported that GOP senator Lindsey Graham was briefed by Waldron himself.

The new subpoena for Waldron comes days after the select committee voted to recommend criminal prosecution for Meadows for his refusal to testify pursuant to a subpoena, and Waldron was unmasked in media reports as the lead author of the coup PowerPoint.

In a statement, Terwilliger said that Meadows’ involvement with the PowerPoint did not go beyond the receipt of the presentation in his inbox, though Waldron’s claims that he met with Meadows numerous times at the White House appear to undercut that characterization.