Cathaoirleach Paddy Burke is recalling the Upper House after Fianna Fáil senator Mark Daly got the backing of a third of his colleagues for the action.
Mr Daly has pushed the issue because he wants to repeal an EU directive on organ donation structures signed into law by Health Minister James Reilly without an Oireachtas debate.
To overturn the law, both houses of the Oireachtas would need to agree by Aug 27, but as it is highly unlikely the Dáil will be recalled, there is virtually no chance of that happening, prompting Government TDs to brand the move an “expensive stunt”.
Mr Daly has called on Dr Reilly to address the special session, as he insists the legislation is flawed.
Coalition TDs claim the move is more to do with giving the Seanad a higher profile in the run-up to the Oireachtas referendum on abolition, than with organ donation laws.
That campaign has seen the gap between the sides narrow, a new poll shows.
Those wanting to scrap the Seanad have dipped three points to 49%, while the number of voters in favour of retention has grown by two points to 36%, with 15% unsure, according to the Red C survey for Paddy Power.
A 58%-42% split is achieved when the “don’t knows” are stripped out.
The poll found Fine Gael and Sinn Féin supporters are more likely to back abolition, with Fianna Fáil and independents likely to want to keep the Upper House.