A mass rally in Togo on Wednesday heaped pressure on President Faure Gnassingbe to enact constitutional reform, as opposition leaders warned against any attempt to delay change.
Amnesty International country head Aime Adi told AFP "at least 100,000" were in the capital, Lome.
Demonstrations also took place in the cities of Sokode, Dapaong and Kara and half a dozen other locations.
Opposition party leader Jean-Pierre Fabre called the demonstration "unprecedented" and estimated that "more than one million people" were on the streets of Lome.
Neither figure was independently verified but AFP journalists on the ground said a tide of people, many of them angry, had converged on the coastal capital, dwarfing previous protests. The population of Togo is 7.6 million, according to the World Bank.
Many brandished placards denouncing the Gnassingbe regime after 50 years in power.
The protests have been called by a coalition of opposition parties, whose leaders vow to continue the protest on Thursday.
Gnassingbe chaired a cabinet meeting on Tuesday evening where ministers approved plans for a bill about restrictions on terms in office and changes to the voting system.
The opposition has been calling for both since 2005, when Gnassingbe succeeded his father, Gnassingbe Eyadema, who ruled for nearly four decades.
Civil service minister Gilbert Bawara told AFP that the government had taken note of the public's "strong expectation" and that a committee was looking into the proposals.
He invited opposition figures to enter into "dialogue and debate" on the issue.
But he said calls to limit the presidential mandate to a maximum of two five-year terms would not be implemented retroactively.
"There is no legislative reason to do so. But we need a consensus so the reform is accepted," he added.
A consensus would mean the approval of four-fifths of parliament, Bawara said.
Parliament does not return from its summer break until October, and exact details of the proposals are vague.
Opposition leaders warned against any delaying tactics or attempts to throw up a smokescreen.
Fabre was greeted with huge applause at the Be Gakpoto intersection, the focal point of riots that broke out in 2005 when Gnassingbe, just 38 at the time, succeeded his father.
"You can stop talking about constitution, you can stop talking about a draft law, it's too late for that, " Fabre said. "Today the door is open. If they don't come out of the house, it will be the people tomorrow who will be going in."
"Unir (Unite, the president's ruling party) calls for talks as soon as it is cornered," said Tikpi Atchadam, the head of the Panafrican National Party.
"I think the people have made up their mind because they're fed up," he added, calling on Gnassingbe to "leave by the front door".
"I don't believe in dialogue with the regime anymore," he said.
One protester, Armand Jarre, 26, said: "The reforms are lies, we don't believe them. If the people's minds are made up, nothing can stop them, not even the army."
One man taking part in the protests said on condition of anonymity that after 50 years ruled by the same family, Togo's problems were "too deep".
Togo was a centuries-long centre for the European slave trade before becoming a German colony in 1884. It was transferred to France after World War I, gaining its independence in 1960.
In 1967, Gnassingbe Eyadema was installed after a military coup, leading to a one-party state. Elections took place in 1993, 1998 and 2003, all of which were either boycotted by the opposition or criticised as unfair.
In 2005, hundreds of people were killed during violent protests after Eyadema's death and his son's succession.
The younger Gnassingbe was re-elected in 2010 and 2015, although the opposition rejected the results.
On August 19, at least two people were killed in protests in Sokode, some 300 kilometres (185 miles) north of the capital.
Togo is heavily dependent on subsistence agriculture and rates poorly for perception of corruption.
The UN Development Programme (UNDP) ranked it 166th in its 2016 Human Development Report, which assessed income, health, education and other factors in 188 countries and territories.
Transparency International, in its 2016 Corruption Perceptions Index, placed Togo 116th in a table of 176 countries.