Over 100 Houses of the Oireachtas secretaries say they will go on strike if TDs and senators contract new higher-paid staff without agreement, SIPTU has warned.
The newly-established Houses of the Oireachtas Commission intends to let politicians hire extra staff starting next year on annual salaries of up to €44,000.
However, the secretaries, whose starting pay is €18,000 a year, are furious and argue they should be able to apply for the new jobs.
Nearly 100 Leinster House SIPTU members told officials on Thursday to prepare for industrial action if the move goes ahead.
"People are very angry that new people would be parachuted in above them ... Should they try to introduce it without agreement, there will be immediate industrial action," said a spokesperson for the secretaries.
The Houses of the Oireachtas Commission was set up earlier this year. During a Dáil debate on the commission three years ago, it was argued that TDs needed researchers to help them with parliamentary duties. However, most have expressed interest in using the new staff in their constituency offices.
Last month, the commission told deputies and senators it was "finalising a package of options, which takes account of the varying needs of individual members in carrying out their parliamentary duties."
Privately, sources close to the commission say they believe industrial relations issues with the secretaries can be resolved in time.
Under the plan, TDs can contract research staff or pool their allowances to hire specialists on a much higher rate of pay. TDs could also opt to take a €33,511 annual fund to hire specialists as required on a fully-vouched basis. Alternatively, TDs could decide to retain their €8,888 secretarial allowance and take a €9,525 allowance to contract expert services as needed.
Senators, on the other hand, can choose one of three options. They can have a full-time secretary each, instead of having to share one between two of them. Secondly, they can take a fully-vouched €16,755 parliamentary allowance to pay for specialist services as required. Lastly, they can retain the secretarial allowance, for which they do not produce receipts and get some extra secretarial help in Leinster House amounting to "an additional 25 per cent of a secretarial assistant".
Meanwhile, TDs are to get a special €4,000 fund to cover extra costs they incur over the next two months for any staff hired in the expectation that the plan would be in force by now. Senators will get a €1,700 allowance.
