Yildirim dismissed claims a Yes vote would end up dividing Turkey.
In remarks made during the ruling Justice and Development (AK) Party's parliamentary group meeting in Ankara on Tuesday, he blamed terror groups such as the PKK and the Fetullah Terrorist Organization for trying to split the country.
Recalling the hard times Turkey went through in 2016, including the July 15 defeated coup, Yildirim said Turkey was now back on track after it learnt its lesson from last year.
“Those planning to darken the future of Turkey are doomed. No power can now block Turkey’s rise. Turkey has taken very firm steps. Despite everything it stays stable, no doubt!” he added.
“They said no to whatever contributed to Turkey’s stable progress. Now they have started a campaign to block the transformation of a democratic Turkey,” he said.
He also praised Turkish people living abroad who were expected to vote Yes in the referendum. Yildirim said the Yes campaign will be embraced from Germany to Turkey’s northeastern border province of Kars.
Millions of Turkish immigrants live in Germany.
Constitutional reform has been under discussion since then-Prime Minister Recep Tayyip Erdogan was voted president in August 2014.
The 18-article bill would hand wide-ranging executive powers to the president and abolish the prime ministerial post. The president would also be allowed to retain ties to a political party.
Other changes would see the minimum age for parliamentary candidates reduced to 18 from 25 and the number of deputies would also rise to 600. Simultaneous parliamentary and presidential elections for a five-year term would be held in November 2019 under the new constitution.