Sturgeon looks set to reopen the issue of Scotland's independence from the UK in talks in Brussels on Wednesday with European Parliament leader Martin Schulz.
Independence is reportedly one of several options being considered to keep the 5-million strong country within the EU, even after the UK leaves the bloc.
Sturgeon has said there can't be months of drift following the June 23 referendum.
Scots voted by 62 percent to 38 percent to stay in the EU in the referendum and voted narrowly to stay in the UK in a referendum in 2014.
Leaving options open
A special motion after Tuesday's emergency debate at Scotland's devolved parliament, Holyrood, will aim to give the Scottish government backing for discussions on options for protecting Scotland's relationship with the EU and the single market.
“I am now determined to explore every avenue to retain Scotland's EU status and today's parliamentary debate is a vital part of that process," Sturgeon said.
"I am specifically asking parliament to strengthen my hand by giving me a mandate to pursue discussions about protecting Scotland's place in the EU with the UK Government, other devolved administrations, EU institutions and member states," she added.
"It is now crucial that our national parliament speaks with as strong and united a voice as possible on this issue. Today's debate is among the most important in Holyrood's history - and I want to see it result in broad cross-party support for our efforts," she said.
EU support likely
Scottish Government Farming Minister Fergus Ewing had informal talks with his EU counterparts in Brussels on June 27 and reportedly received a "sympathetic hearing" over Scotland's bid to remain in the EU.
Ewing said senior European officials told him that they would like to see Scotland as the EU's 28th member state.
Scotland cannot block Article 50
Sturgeon has indicated she would consider asking Scottish lawmakers to block legislation paving the way for Brexit, although Former First Minister of Scotland Alex Salmond subsequenty said the Scottish Parliament cannot block Brexit.
Westminster, he said, would be able to override any move by the Edinburgh parliament to veto the UK leaving the EU.
Sturgeon is expected to argue that backing the Scottish government motion is not the same as supporting a second referendum.
Schulz talks first
Sturgeon's direct talks with Schulz will reportedly go ahead without any British officials being present.
She will also meet other EU leaders - including Guy Verhofstadt, former prime minister of Belgium - many of whom believe it is wrong Scotland be taken out of the EU against its will. The talks are expected to explore whether special arrangements can be made for Scotland not to have to apply for membership from the outside.
Juncker talks later
An official spokesman for the Scottish leader said she will not meet Jean-Claude Juncker, the European Commission president, but that they are expected to hold talks shortly.
Juncker told television in Luxembourg he will speak to Sturgeon in the coming days and his spokesman said there was a "very open door" to talks with her.
EU diplomatic circles are reportedly alarmed by Juncker's attempts to woo the Scottish National Party (SNP) to put pressure on UK Prime Minister David Cameron.
jbh/kl (Reuters, AP)