Update- 8pm: Fine Gael will back President Michael D Higgins for a second term in office.
President Higgins now has the backing of both Fine Gael and Fianna Fáil.
At a parliamentary party meeting this evening, Fine Gael TDs and Senators decided not to run their own candidate and to support the incumbent President.
It means Sinn Féin may be the only large party to run a candidate in the election.
The party's Ard Comhairle will make a decision on Saturday.
The backing of Michael D Higgins by Leo Varadkar and Micheál Martin will make it very difficult for Independent candidates to even get on the ballot.
TDs, Senators and councillors from those two parties won't be allowed to facilitate any candidates.
Meaning those seeking to get the backing of the required 20 TDs or Senators or four local councils will have an uphill battle even to have the chance to challenge Michael D.
Fine Gael TDs and Senators vote to support Michael D Higgins for a second term as president. Taoiseach Leo Varadkar says they may put party money behind the campaign pic.twitter.com/jNBjIBInuC— Seán Defoe (@SeanDefoe) July 11, 2018
Earlier: Taoiseach: FG decision on whether to contest presidential election 'not a simple one'
Fine Gael councillors will be expected to support Michael D Higgins if the party decides to back him for a second term as President.
The parliamentary party will meet this evening to decide whether or not to run a candidate.
It is expected they will opt to back Mr Higgins in his re-election bid.
Taoiseach Leo Varadkar says elected reps will be expected to back the decision, and not allow Independent candidates into the race.
Mr Varadkar said: "Obviously the decision isn't a simple one as to whether we're contesting or not contesting the election, it's also a decision as to whether we are going to actively support one candidate or not.
"If we decide to actively support a candidate, that would mean active support, not assisting other candidates and contributing to the campaign in all the ways that you normally do in an election campaign."