Syria's President Bashar al-Assad has called a constitutional referendum that would effectively end nearly 50 years of single-party rule, according to state media, amid assaults by security forces on Hama and other opposition strongholds.
A day after rejecting UN allegations of crimes against humanity, Assad called the referendum for February 26.
The proposed charter drops Article 8, which declared the ruling Baath Party as the "leader of the state and society", allowing for a multi-party system, state television said on Wednesday.
The president, who must be a Muslim man, can serve a maximum of two seven-year terms, although it is unclear if this would apply to Assad, who is already in his second term.
In April, Assad ended emergency rule, in force since 1963 when the Baathists took power in a coup d'etat. But he has repeatedly promised reforms that have failed to materialise since the uprising erupted in March.
The 46-year-old Assad, who succeeded his late father Hafez in 2000, has said the constitution would usher in a "new era" for Syria, the SANA state news agency said.
"When the new constitution is approved, Syria will have passed the most important stage" of reforms, bringing a "brilliant future for next generations," Assad was quoted as saying.
While the US dismissed the move as laughable, Russia, a major weapons supplier to Damascus, welcomed it.
Jay Carney, the White House spokesman, said "it's actually quite laughable - it makes a mockery of the Syrian revolution.
"Promises of reforms have usually been followed by an increase in brutality and have never been delivered upon by this regime since the beginning of peaceful demonstrations in Syria".
He said the "Assad regime's days are numbered".
In-depth coverage of escalating violence across Syria
By contrast, Sergei Lavrov, the Russian foreign minister, said: "We certainly believe a new constitution to end one-party rule in Syria is a step forward. It is a welcome idea and we hope the constitution will be adopted."
China and Russia have faced heavy criticism for blocking a second UN Security Council resolution condemning the Assad government.
As diplomats said they would seek to condemn the violence at the UN General Assembly on Thursday, France said the world body should consider setting up "humanitarian corridors" to get aid to Syrians caught up in the violence.
Alain Juppe, the French foreign minister, said that Russia was isolating itself after its veto of a UN resolution on Syria, adding that he would try to convince his Russian counterpart to change tack.
Juppe said it would take "all my powers of persuasion" when he meets Lavrov in Vienna, Austria, on Thursday.
And Tunisia voiced hope for "a consensus and unified message in favour of political change" at a "Friends of Syria" conference that it hosts on February 24.
For its part, Egypt called for change in Syria that met its people's demands, while ruling out supporting outside military intervention.
Egypt has backed Arab League resolutions demanding Assad step aside but diplomats say it is wary of the diplomatic push from Gulf states, whose latest plan to end the crisis could open the door to arms shipments to the opposition.
"The situation in Syria is deteriorating quickly ... The time has come for the required change to avoid a complete explosion in the situation in Syria," Mohammed Kamel Amr, Egypt's foreign minister, said.
Syrian activists fill the information gap, as many foreign journalists remain banned from the country
The opposition Syrian National Council (SNC) is likely to reject the new constitution, given that one of its main guiding principles is "to overthrow the regime using all legal means".
Regardless, the proposed charter rules out most of the opposition as it bans religious parties and dual nationals, preventing the SNC, which includes the Muslim Brotherhood, and most of its leadership from running for office.
Assad's announcement came as activists said troops stormed the central city of Hama and stepped up assaults nationwide, defiant in the face of mounting Arab and Western peace efforts.
Further to the south, an explosion struck an oil pipeline at daybreak in the flashpoint city of Homs, with activists saying government forces bombed it from the air and state media blaming "armed terrorist gangs".
The blast sent up columns of black smoke over the central city, YouTube footage showed.
Syria's government has attributed several similar attacks to foreign-backed "terrorists", but the opposition accuses it of destroying energy infrastructure to punish protesters.
Assad's forces appear to have refrained from using air power to crush the opposition to avoid a no-fly zone being imposed over the country.
On the ground, however, troops launched an assault on the city of Hama, just north of Homs, where loud blasts could be heard in the Hamidiyeh and other neighbourhoods, activists said.
The number of people killed on Wednesday had risen to 20, the Local Co-ordination Committees (LCC), one of the main co-ordinating bodies behind the uprising, said.
The LCC reported that 11 people died in Idlib, four in Homs, three in Deraa and one each in Aleppo and Barzeh, a Damascus suburb.
Salem Sheikh Al Ard, a political activist in Barzeh, told Al Jazeera that his neighbourhood had been surrounded by security forces.
"The fourth armoured division and the republican guard began cordoning off areas and arresting civilians in the streets.
"This operation came in reaction to the daily protests that have been going on. It is against the defectors and the member of the Free Syrian Army who protect the people in these protests."
Rights groups say more than 6,000 people have been killed since government forces began cracking down on democracy protests launched 11 months ago to the day.