The DUP will have little influence at Westminster while "double-jobbing" MPs continue to sit at Stormont, an arch critic has said.
Traditional Unionist Voice (TUV) leader Jim Allister made the remarks during the launch of his party's General Election manifesto in Antrim
The DUP is Northern Ireland's largest party and could return up to 10 MPs. In 2010 it pledged to end double jobbing.
Mr Allister said: "If you are going to have an influence you have to be there, they have to address this issue of double jobbing.
"The DUP presently has two double jobbers who seem to think it is enough to turn up on a Wednesday (at Westminster) when Stormont is not sitting."
Sammy Wilson, former East Antrim MP, missed two-thirds of the votes in the last parliament. He was finance minister in the powersharing ministerial Executive until August 2013 and still holds a seat in the Northern Ireland Assembly.
Party colleague, ex-East Londonderry MP Gregory Campbell, is also a member of the devolved institution.
Mr Allister also criticised the mandatory coalition at Stormont which he claimed had damaged democracy.
He said DUP South Belfast candidate Jonathan Bell and North Down hopeful Alex Easton should clarify whether they intended to give up their Assembly posts if elected.
The vote on the European Arrest Warrant and the creation of three-parent babies were among those missed by Northern Ireland MPs, the TUV manifesto said.
Before the 2010 election, during which DUP leader Peter Robinson lost his seat, all except Mr Robinson pledged to give up their second seats.
Mr Allister said: "The electorate in East Belfast took care of the first issue but two other MPs brazenly defied their solemn commitments and have continued with double jobbing and seem to be prepared to stretch it to the very end."
Most Northern Ireland responsibilities, except those like national security, foreign affairs and taxation have been devolved from Westminster to Stormont.
The five main parties in Northern Ireland are seeking devolution of corporation tax to reduce the rate to compete with the Republic of Ireland for foreign direct investment.
The TUV manifesto said: "We have a system of government which shackles us to the bankrupt Republic by way of multiple North/South bodies, while we fail to exploit the advantages of being part of one of the world's biggest economies as part of the UK."
It added: "For Sinn Fein, of course, the opportunity to cut fiscal ties to London is irresistable and trumps any professed concern for public sector workers - who will be hit by cuts to the block grant. Sadly, the DUP and UUP helped them on with it.
"TUV believes the UK should retain its unified taxation system. That is the natural unionist position and it also makes sound fiscal sense for Northern Ireland."
The party has one Stormont Assembly member, Mr Allister, who is not standing for Westminster. It is fielding seven candidates.
Its manifesto advocated cutting the foreign aid budget, more defence spending and introducing an Australian-style points system for immigrants.
Mr Allister, a former MEP, said the UK would be better off outside the EU.
He called for the establishment of a voluntary coalition and opposition at Stormont and opposed the devolution of further powers.
Mr Allister claimed the First Minister had a Sinn Fein "ransom letter" on his desk seeking more money for welfare at the expense of education and health and claimed the republican party would only come back for more concessions.
The manifesto said: "We are alarmed at the growing tendency among some unionist representatives towards a sense of 'Ulster nationalism' and the ease with which some assist Sinn Fein in insisting that the rest of the UK owes us a living. We want to strengthen the unity of the UK, not further undermine it."
The TUV leader downplayed the DUP's role in a hung parliament.
"The DUP have over-hyped the role they are likely to play, it is going to be the larger blocks, two dozen or more MPs, which have a real influence."
He said he wanted the UK to be "liberated from the clutches of the EU".
"That is the path to the re-birth of the UK so that this country can once again control its own borders and decide its own socio-economic policy, be liberated from the dead hand of oppressive regulation from Brussels."
A DUP spokesman said: "In 2010 we made it clear that only two DUP MPs would remain at Stormont and it would be phased out entirely by the next Assembly election.
"It is clear that the DUP is the only party from Northern Ireland which can have real influence in the next Parliament.
"Across the province people are increasingly recognising only a strong team of DUP MPs can deliver the best possible deal for Northern Ireland."