By Angel Krasimirov
SOFIA (Reuters) - Bulgaria's Socialists said on Saturday they would form a broad coalition if they win a parliamentary election on May 12 and cut taxes for the lowest earners to try to raise living standards.
Thousands of supporters of the Bulgarian Socialists Party (BSP) waved red flags and balloons, and chanted "Victory", filling a park in Sofia at the start of the election campaign.
The centre-right GERB party of Boiko Borisov, forced from power in February by protests over living standards and corruption, has pledged to keep taxes unchanged and boost incomes only in line with economic growth.
GERB is extending its opinion poll lead with support at 22-24 percent, compared to 17.4-17.5 percent for the Socialists.
But Borisov's party is unlikely to command a majority and has said it will attempt to form a minority government.
"I know that you do not want another government led by Boiko Borisov," BSP leader Sergei Stanishev told supporters. Stanishev was prime minister from 2005 and 2009.
"Bulgarians will be able to vote for a government that will have broad parliamentary support as it will not be a single-party government and it will work for the progress of Bulgaria and to lead the country out of this crisis," Stanishev said.
Former Finance Minister Plamen Oresharski is the BSP's choice to be the next prime minister, Stanishev said.
BSP will try to improve living standards in the European Union's poorest member by cutting taxes for low earners and trying to create more than 250,000 new jobs, Stanishev said. The jobless rate jumped to 11.8 percent in March from less than 6 percent at the end of 2008.
In March, President Rosen Plevneliev appointed respected diplomat Marin Raikov as interim prime minister and he pledged to retain fiscal discipline with a cabinet of professionals that aims to shore up confidence rattled by protests.
(Reporting by Angel Krasimirov; Editing by Jon Hemming)