The House select committee investigating the Capitol attack is weighing whether to subpoena some of Donald Trump’s top allies on Capitol Hill as it considers its options on how aggressively it should pursue testimony to move forward its inquiry into the January 6 insurrection.

The Republican House minority leader Kevin McCarthy and Republican members of Congress Jim Jordan and Scott Perry may have inside knowledge about Trump’s plan to stop the certification of Joe Biden’s election and whether it was coordinated with the Capitol attack.

But the outright refusal of McCarthy and the other Republican lawmakers to testify voluntarily with the investigation has intensified discussions among the panel’s members and investigators about whether to force their cooperation.

The select committee is undecided on whether to take that near-unprecedented step, in part because of one major concern that has emerged in recent days, according to two sources familiar with the matter: Republican retaliation against Biden and Democrats in future inquiries.

In private conversations, some members and investigators on the select committee have expressed how appalled they are at the refusal of McCarthy and the Republican lawmakers to help the investigation, and feel prepared to subpoena for their testimony, the sources said.

But the one major recurring worry raised in discussions, the sources said, is that subpoenas might create moral hazard for Republicans plotting an onslaught of partisan investigations into the Biden administration should they retake the House after the 2022 midterms – as many observers think likely.

Republicans in Congress have openly floated the prospect in recent days of launching political probes into the Biden administration’s coronavirus response, the withdrawal from Afghanistan, the personal life of Biden’s son Hunter, as well as an impeachment inquiry.

In response, some members and investigators on the select committee have quietly raised the possibility that if the panel declines to subpoena Republicans now, then a Republican majority might not subpoena Democrats in the future, the sources said.

The issue has proved a difficult conundrum for the select committee, which started serious discussions about subpoenas to Republicans after Jordan and Perry refused to cooperate, and escalated the urgency of talks after McCarthy also declined to help the inquiry.

The panel was particularly outraged by McCarthy’s refusal and his statement attacking their request for an interview as “abuse of power” and intensified its research into parliamentary rules governing their ability to authorize subpoenas, the sources said.

Even in the absence of any formal decision, the possibility of subpoenas has already become a touch point as the select committee grapples with the so-called speech and debate clause in the constitution that shields lawmakers while they perform their official duties.

The clause says lawmakers “shall not be questioned in any other place” about speech or debate, and is generally interpreted to cover all legislative actions – which Republicans argue precludes them from having to answer the select committee’s investigation.

But the members on the panel believe the law does not extend to protect lawmakers from Congress’s own investigations, rejecting the idea that McCarthy, Jordan and Perry have any claim to immunity as the panel investigates whether Trump oversaw a criminal conspiracy.

There is also precedent for the House to subpoena its own members. The House ethics committee, which investigates allegations of wrongdoing by members of Congress, for instance has the authority under House rules to subpoena lawmakers – orders they cannot refuse.

A spokesperson for the select committee declined to comment on internal discussions about how aggressively the panel might act to secure cooperation from McCarthy, or whether counsel for the panel has reached a determination on the matter.

Congressman Bennie Thompson, the chairman of the select committee, previously said in his request for cooperation to McCarthy that the panel was interested in details about McCarthy’s conversations with Trump before, during and after the Capitol attack.

But it is also not immediately clear whether McCarthy would have substantially new information to share with House investigators beyond what is already public – meaning the marginal benefit to getting his testimony may not outweigh the potential political consequences.

There remains a possibility that McCarthy, Perry and Jordan might cooperate with the select committee in the event of a subpoena, using the potential legal threat to justify their reversals to Trump, who the Guardian reported last month is agitated by the investigation.

If the select committee decides it has the authority and resolve to issue subpoenas, the sources said, then the primary remaining question would likely be a matter of timing, and when best in the investigation the panel should force their cooperation.

But the worry about Republican retaliation reflects the select committee’s recognition that the stakes of issuing subpoenas to Republican lawmakers and McCarthy, the man poised to become speaker in 2022 should his party retake the House majority, could not be higher.

Additional concerns have centered on the ability to enforce subpoenas to Republican lawmakers if the select committee did take that step, and whether a federal judge would countenance becoming mired in what is essentially becoming a partisan fight in Congress.

Congressman Adam Schiff, a member of the select committee, suggested on MSNBC the panel, for that reason, would likely not pursue criminal contempt of Congress proceedings with recalcitrant lawmakers as it did with Trump’s former aides Mark Meadows and Steve Bannon.

Moving ahead with criminal contempt of Congress against the Republican lawmakers would mark an escalation that tests the limits of congressional subpoenas, threatening to touch off a legal fight the panel might not have time to conclude as it races to finish its report.

The former Republican chairman of the House oversight committee, Trey Gowdy – who also oversaw the inquiry into former Secretary of State Hillary Clinton’s emails – demurred on subpoenaing Democrats over concerns about enforceability, a source close to Gowdy said.

Gowdy faced internal pressure from the House Republican conference for his reluctance to subpoena Democrats, the source said, but that was in part to make sure lawmakers would not defang the power of congressional subpoenas if they simply refused to comply.

That leaves the select committee with only a handful of options, which appear to rest on a gamble over whether it can shame Republicans into cooperating, including a formal resolution on the House floor censuring or admonishing the lawmakers.