"Erdogan knows it's on a knife-edge…" Michael Taylor, senior analyst at Oxford Analytica, told CNBC in a phone interview.
"The Dutch and German developments really benefitted Erdogan… I mean he is a terrific campaigner, he engages with the people and his finger is really on the pulse, so I suppose he is a good populist in that sense," Taylor added.
Erdogan's international campaign for a Yes vote has received widespread disdain. Turkey's leader embraced a bitter row with his European neighbors and even described Dutch and German authorities as behaving like Nazis.
Erdogan has resolutely campaigned for Turkish citizens living abroad to back him in the vote and so the Netherlands and Germany's decision to bar Turkish officials from attempting to rally support in their respective countries sparked fierce criticism from Turkey's president.
Two Turkish opinion polls published Wednesday showed a slim majority for the Yes campaign with around 51 to 52 percent of citizens saying they would vote in favor of the constitutional reforms proposed, according to a Reuters report.
"I think Erdogan will score a narrow victory, similar to Brexit," Chatham's Hakura predicted.