But the Arab League-organised conference of Arab and Western officials, including US Secretary of State Hillary Clinton, will be marked by a Russian boycott and the absence of China.
Both countries have frustrated Western and Arab efforts to rein in President Bashar al-Assad's regime, including by vetoing UN Security Council resolutions.
"We look forward to concrete progress on three fronts: providing humanitarian relief, increasing pressure on the regime, and preparing for a democratic transition," Clinton told reporters in London.
"To that end, we hope to see new pledges of emergency assistance for Syrians caught in Assad's stranglehold, and international coordination and diplomatic pressure on Damascus to allow it to get to those who need it most."
A US official said Arab and Western powers at the meeting will challenge Assad's regime to accept a proposal to allow in desperately needed humanitarian aid.
"I think one of the things you are going to see coming out of the meeting tomorrow are concrete proposals (on the supply of aid) within days," the official said on condition of anonymity.
French Foreign Minister Alain Juppe also said a key goal was "to move forward on the question of humanitarian aid."
"I put forward the idea of humanitarian corridors. This cannot be abandoned. We must see how this can be put into place," he told London-based pan-Arab newspaper Al-Hayat.
The draft declaration demands that humanitarian groups be allowed in to Syria to assess the need for aid and "be permitted to deliver vital relief goods and services to civilians affected by violence."
"We hope for a solution as soon as possible because the humanitarian situation is urgent," International Committee of the Red Cross spokesman Hicham Hassan told AFP as international organisations met in Geneva to discuss how to get aid into Syria.
Juppe said the meeting will aim to "increase pressure on the regime" and send a signal not just to Assad but also to the countries that have backed him.
The meeting "will be a very strong symbol of the growing isolation of the regime and the isolation of those countries that continue to block all solutions at the Security Council," he said.
British Foreign Secretary William Hague said London would push for the Tunis talks to agree to "tightening a diplomatic and economic stranglehold on the Assad regime" with increased sanctions.
EU diplomats have said the bloc is set to slap fresh sanctions on Damascus, including a ban on Syrian-run cargo flights, a freeze on the assets of Syria's central bank and restrictions on trade in precious metals.
The draft declaration called for a toughening of sanctions including with travel bans, asset freezes, ceasing oil purchases and the closure of foreign embassies in Damascus and Syrian embassies in other capitals.
It also called for the Arab League to convene a meeting of the Syrian opposition and praised the Syrian National Council (SNC), the main opposition umbrella group.
But it did not appear to give the SNC exclusive recognition, calling it only "a legitimate representative of Syrians seeking peaceful democratic change."
SNC representatives and other opposition groups at Friday's meeting are expected to come under pressure to work for the creation of a united group to represent opponents of the regime.
Clinton on Thursday described the SNC as a credible representative of the Syrian people.
"We believe that the Syrian National Council, which will be there sitting at the table, will show that there is an alternative to the Assad regime," she said.
"The consensus opinion by the Arab League and all the others who are working and planning this conference is that the SNC is a credible representative," Clinton said.
Juppe however said the opposition still had work to do.
"It is fundamental that they get organised, that they group together," Juppe said.
"We are in a situation where there is one opposition inside (the country), one opposition outside and military structures that are, in all honesty, not very organised."
Activists say more than 7,600 people, mostly civilians, have died since Assad's hardline regime launched a crackdown to snuff out a revolt that began with peaceful protests in March 2011.
Syrian forces launched another massive bombardment of rebel districts in Homs on Thursday, pounding the city for the 20th straight day, activists said.