Turkey's opposition vowed on Monday to undo President Recep Tayyip Erdogan's two-decade legacy of Islamic-rooted rule and expand democratic freedoms if they take power in crucial May 14 elections.

The six parties united against Erdogan also pledged to decide on February 13 on a joint candidate in the presidential vote -- widely seen as Turkey's most consequential in generations.

The opposition's 2,300-point programme aims to roll back many of the powers Erdogan has wrested from parliament and ministries in the latter years of his tumultuous rule.

It limits the president to a seven-year term and makes an empowered new prime minister accountable to lawmakers.

"We will shift to a strengthened parliamentary system," the programme says.

"We will put an end to the president's power to issue decrees."

Turkey's role as a strategic member of NATO and key player in wars ranging from Syria to Ukraine makes the upcoming vote vital for its traditional Western allies.

Erdogan has developed increasingly close relations with Russian President Vladimir Putin while tightening social freedoms and flouting European court rulings to free his jailed opponents.

Western powers have tried to stay out of the election to avoid drawing Erdogan's ire.

But US President Joe Biden suggested in a TV interview conducted during his 2020 election campaign that Washington should help "elements" of the Turkish opposition "take on and defeat Erdogan".

Close race

Erdogan began his rule in 2003 as prime minister and was elected president -- at the time a more ceremonial post -- when his mandates ran out in 2014.

He then rammed through constitutional changes in 2017 that eliminated the premiership and created a powerful new executive which allowed the president to effectively rule by decree.

The opposition pledged to change the constitution back to the way things worked throughout most of Turkey's post-Ottoman history.

Constitutional changes can be ratified by 400 votes in the 600-seat parliament.

They can also be put up for a national vote if the opposition gathers the 360 votes needed to trigger a constitutional referendum.

The opposition's pledge to rewrite the constitution adds particular importance to the legislative polls being conducted alongside the presidential ones.

Opinion polls point to a tightly contested election that is too close to call.

Constitutional referendum

The opposition pledged to "urgently" amend the constitution and "put an end to the vague and arbitrary restriction of the freedoms of assembly and demonstration".

Erdogan unleashed sweeping purges after a failed 2016 coup attempt that curbed many of the freedoms enjoyed under his more prosperous and popular first years of rule.

Analysts estimate that 90 percent of Turkey's media is now under the control of the government or its business allies.

Thousands of activists -- many of them Kurds -- are languishing in prison on terror-related charges that rights groups believe Erdogan is using to crack down on political dissent.

The opposition's programme was unveiled at a ceremony attended by cheering crowds eager to reverse Erdogan's transformation of Turkey into a more religiously conservative state.

EU membership 

Some of the biggest applause came from promises to crack down on corruption and restore the strength of Turkey's traditional institutions -- including its state media.

The opposition vowed to make Turkey's TRT national broadcaster and Anadolu state news agency abide by "the principles of independence and impartiality". Neither issued an immediate response.

Its foreign policy section stressed the importance of restoring "mutual trust" with the United States and achieving Turkey's stalled goal of gaining "full membership in the European Union".

It made no direct mention of Russia's invasion of Ukraine.

"We will maintain relations with the Russian Federation with an understanding that both parties are equal and strengthened by balanced and constructive dialogue at the institutional level," the programme said.

Erdogan's refusal to join Western sanctions on Moscow has turned Turkey into a key route for Russia to access foreign goods and services.

The resulting boom in bilateral trade has added to Erdogan's tensions with Washington and the European Union.