Donald Trump stood firm on his decision to install controversial loyalist Bill Pulte as the country’s top intelligence official, demanding Congress pass a short-term extension of a surveillance law set to expire amid intense criticism of the appointment.

Pulte will has been asked “to execute the immediate and needed downsizing” of the office of the director of national intelligence, the US president declared on Wednesday, after lining him up to serve as acting director on a temporary basis.

In a Truth Social post, Trump accused Democrats of playing politics with the country’s safety after US senators – including seven Republicans – blocked the extension of a powerful government surveillance program.

Section 702 of the Foreign Intelligence Surveillance Act (Fisa), which permits US intelligence agencies to collect communications of foreign targets operating outside the country without a warrant, is due to expire later this week.

“FISA 702 is very important to our Military, and keeping the American People safe, especially during the World Cup and America250 Celebrations,” wrote Trump. “If nothing is done, this important Law will expire this week. I am asking Congress to send me a short-term extension of FISA to provide time for the selection and confirmation of a permanent Head of the Agency.”

Trump’s announcement came a day after he met with Mike Johnson, the US House speaker, to discuss Pulte’s elevation to the role, which has prompted widespread concern over his complete lack of national security experience and the prospect that he could use the office’s spying powers to continue his campaign of targeting Trump’s perceived political enemies.

Writing on social media on Tuesday evening, Trump said Pulte was already working with the outgoing director, Tulsi Gabbard, and will take her place on 19 June, while remaining the head of the federal mortgage agency.

Gabbard, a former congresswoman who served in the military and then on a House subcommittee with oversight of military intelligence, had announced in her resignation letter that she would step down on 30 June.

Trump offered no explanation for Pulte taking over before that date, but the president has suggested in public comments that he expects his political ally to investigate elections that he has falsely claimed were “rigged” once he is installed as the country’s top intelligence officer.

While Trump has insisted Pulte would only serve in the role for a “short period”, many Senate Republicans are urging the White House to name a full-time nominee who can be confirmed by the chamber. Elevating Pulte to the post on an acting basis avoids a contentious confirmation process.

Democratic lawmakers immediately said the appointment of Pulte would scuttle a bipartisan agreement to renew section 702 of the Foreign Intelligence Surveillance Act, which is due to expire on Friday.

The powerful intelligence tool has long attracted controversy, since the program targets foreign nationals whose messages may pass through US servers or involve US contacts, meaning a wide array of domestic communications can be swept up without a warrant ever being sought.

The FBI in 2020 was discovered using section 702 to investigate whether protesters involved with Black Lives Matter had any ties to terrorists, according to a declassified memo released by the office of the director of national intelligence in 2023, a seat that would soon be filled by Pulte.

Hakeem Jeffries, the House Democratic leader, said on Tuesday that if Trump installs Pulte, Democrats will not allow the surveillance law to be reauthorized.

“Bill Pulte is deeply unqualified to serve as acting director of national intelligence and is deeply dangerous,” Jeffries told PBS NewsHour.

“He’s got no national security experience, no military experience and no law-enforcement experience. In fact, the statute explicitly requires that any person occupying this position of great sensitivity have national security experience in their professional background. Bill Pulte has zero of that.”

“He’s also someone who has clearly demonstrated a willingness to weaponize the federal government against Donald Trump’s perceived adversaries,” Jeffries, who could be the speaker of the House next year, said. “So under no circumstances should we trust the privacy interests or national security interests of the American people with Bill Pulte on top of Donald Trump and Kash Patel.”

As head of a federal mortgage agency, Pulte has used his access to private financial information to accuse public officials Trump dislikes of mortgage fraud, including the Democratic New York attorney general, Letitia James; Senator Adam Schiff, a California Democrat; and Lisa Cook, a board member of the Federal Reserve, who was nominated by Joe Biden.

The case against James was dismissed, and the referrals against Schiff and Cook have yielded no criminal charges.

“Donald Trump needs to withdraw his decision to elevate Bill Pulte,” Jeffries said. “That’s a starting point, not an ending point, and then we can see if we can responsibly get to a place where there are enough reforms built into the law to provide guardrails and protect the American people.”