The agreement was reached during a friendly dinner at the presidential residence in Brazilian capital Brasília with the participation of the main leaders of the PMDB and the PT (Workers Party), the president's own party, as well as Rousseff, who is the current chief of staff for the presidency.
PMDB chairman Michel Temer said that the "political agreement" entails support from the conservative party for the candidacy of Ms Rousseff and naming her companion in the presidential ticket.
However Temer added that the PMDB, PT "marriage" must have the approval from both parties' conventions which will take place sometime at the end of 2009 or beginning of next year.
Temer, who is currently president of the Lower House, is mentioned inside PMDB as the most probable name for the second person of the 2010 presidential ticket next to Rousseff.
"The name of the vice president (hopeful) will be decided by political circumstances to be defined next year," said Temer who underlined that more important is to bring other parties of the current government coalition in support of Ms Rousseff.
Another ten parties of all sizes, ideological background or representing interest group make up the coalition which supports Lula.
"It would be most useful to have a block of parties supporting the candidacy of the minister," pointed out Temer.
PMDB joined the government coalition back in 2005 when Lula's Workers Party was rocked by major scandals involving massive handouts to members of Congress to have bills passed. Since then the PMDB has consolidated as the most influential party in the ruling coalition.
Temer has also managed to make it the strongest electoral force in Brazil which was ratified in the governors' election of 2006 and municipal of 2008.
In 2006 when the PMDB backed the reelection of President Lula, the PMDB won 7 out of 27 governorships and in 2008 took control of 1.201 town halls out of 5.563.
The PMDB also holds the presidency of the Lower House and of the Senate with a most controversial figure, but still very influential, José Sarney, a former president of Brazil.
Congressional sources in Brasília quoted in the press anticipate that at least five of the small parties from the ruling coalition will throw their weight behind Ms Rousseff.
But above all Ms Rousseff will be "Lula's candidate", since he happens to be the most popular president in recent Brazilian history with a public opinion polls sustained support of almost 80%, and could easily have forced a constitutional amendment to have him elected for a third consecutive mandate.
Mercopress