A total of 68 MPs have so far signed a Commons motion demanding a debate on the withdrawal of Sinn Féin's allowances and facilities at Westminster in light of last week's report by the Independent Monitoring Commission (IMC).
Two former ministers - Ms Kate Hoey and Mr Frank Field - are among at least seven Labour and Liberal Democrat MPs backing the Early Day Motion (EDM) sponsored by Conservative Northern Ireland spokesman, Mr David Lidington, the DUP leader, the Rev Ian Paisley, and Ulster Unionist leader, Mr David Trimble.
And pressure on the issue seemed set to build last night after Northern Ireland security minister, Mr Ian Pearson, told MPs the government would keep it "under review", while reminding them that it was "also a matter" for the House of Commons itself.
During Northern Ireland Questions yesterday Mr Lidington also pressed the Secretary of State, Mr Paul Murphy, to say whether - having accepted the IMC's report and recommendations - it was now prepared to consider reconvening the Stormont Assembly while excluding Sinn Féin from Executive office.
Mr Murphy also found himself under Conservative, DUP and Ulster Unionist pressure over the government's apparent failure so far to press Libya for details of weapons previously shipped to the IRA; the details of the failed negotiation between the two governments and pro-Agreement parties preceding last November's Assembly election; and the cancellation of this week's planned proximity talks on the initiative of the Irish Government.
Mr Lidington observed that, had the Assembly been sitting, the IMC would have recommended sanctions "up to and including" Sinn Féin's exclusion. And he asked if, having accepted the report, the government would consider reconvening the Assembly and doing precisely that.
Mr Murphy told him: "No, it does not mean we're going to do that immediately."
Pressed by Mr Lidington to say why the Taoiseach's "principle" that Sinn Féin was not yet fit to serve in government in the Republic should not equally apply to a devolved Executive in Belfast, Mr Murphy replied, "the reality is that that is why the Assembly is still suspended" and that paramilitarism remained "the obstacle" to be overcome.
Later in the Commons the prime minister, Mr Tony Blair, resisted a call from former SDLP leader, Mr John Hume, for an immediate public inquiry into the murder of Mr Pat Finucane, while repeating that he stood by the commitments given during the Weston Park negotiations.
Mr Murphy and Mr Pearson side-stepped a number of questions about whether they had yet opened discussions with the Foreign Office about the need to press for details of weaponry supplied by Colonel Gadafy to the IRA, following the restoration of relations between the UK and Libya.