Almost 185,000 people are entitled to vote in byelections in the Dáil constituencies of Meath and Kildare North tomorrow.
Seven candidates will run in each constituency. In Meath, the candidates are Sirena Campbell (Progressive Democrats), Shane Cassells (Fianna Fáil), Dominic Hannigan (Labour), Shane McEntee (Fine Gael), Fergal O'Byrne (Green Party), Liam Ó Gogáin (non-party) and Joe Reilly (Sinn Féin).
The candidates running in Kildare North are Aine Brady (Fianna Fáil), Paddy MacNamara (Labour), Catherine Murphy (non-party), Seanán Ó Coistin (non-party), JJ Power (Green Party), Darren Scully (Fine Gael), and Kate Walsh (Progressive Democrats).
The elections are being held to fill the seats vacated by the former minister for finance Charlie McCreevy in Kildare and by former taoiseach John Bruton in Meath.
Mr McCreevy was appointed EU Commissioner for the Internal Market; Mr Bruton was appointed EU ambassador to Washington.
The polling stations will open at 7am in both areas and will remain open until 10pm to allow the maximum number of people to vote. Both constituencies are in the Greater Dublin commuter belt, with thousands of potential voters travelling to and from work in the capital each day.
Major issues in the byelection include transport problems and commuting, childcare and the proposed route of the M3 motorway between Clonee and Kells in Meath.
A total of 65,080 people are registered to vote in Kildare North; 119,265 are registered in Meath, with a further 285 on a supplementary register.
The number of voters in both areas has risen by 20 per cent since the 2002 general election as the counties have witnessed an explosion of new housing and development.
Counting for the Meath vote will begin at 9am on Saturday morning at Simonstown Gaels GAA club in Navan. The Kildare vote will be counted from 9am at Sallins GAA Club. A result in both constituencies should be available by late afternoon, barring any recounts.
The Government will be watching the results closely - no Government party has won a byelection in more than 20 years.
Fianna Fáil holds three of the five seats in Meath. The other two seats are held by Fine Gael. In Kildare North, the three seats are held by Fine Gael, Fianna Fáil and Labour.