Paroubek, the 53-year-old deputy mayor of Prague and a former manager, has led a recent resurgence of his leftist party after a clear-out to try to end months of political scandals that knocked it to near single-digit popularity.
With the rightist opposition and the left in a dead heat in surveys, a grand coalition of the main left and right parties - similar to one that emerged after Germany's recent election - is a strong possibility after the election due next June.
But the combative Paroubek told Reuters in an interview that he preferred the idea of co-operating with the Communist Party - which has not distanced itself completely from the totalitarian predecessor that ruled Czechoslovakia for over four decades.
"I think that it is cleaner than the option of a grand coalition. In Germany, it was a way out of trouble," he said.
The rightist Civic Democrats, who are cooler toward European integration than the current government, have also spoken against a grand coalition.
Since taking over the cabinet in April from Stanislav Gross, who resigned amid allegations of corruption, Paroubek has used strong rhetoric, clashes with political foes and tireless travels to revive his party's fortunes.
His efforts have won him the nickname "The Bulldozer" in the press. They have also struck a chord with the electorate, boosting the party's ratings to around 24 percent from a low of 11 percent, and made him the country's most popular politician.
His party still trails the opposition Civic Democrats, who have around 32 percent.
But the combined left, including the Communists, now has around 40 percent in surveys, level with the combined right of Civic Democrats and Christian Democrats. This suggests either left or right might be able to command a majority in parliament.
Paroubek, who says he has the same vision of a social state as French President Jacques Chirac, declined to say how far he would go in negotiating support from the Communists - a tricky question since many Czechs still abhor the notion of allowing them even a share of power.
"The Social Democrats will ensure the democratic institutions of this country remain intact," he said, adding that cabinet posts or executive positions for the Communists were "out of the question, I think that is clear".
The Communists, starved of power for over a decade, are already on record as saying they would be prepared to consider supporting the Social Democrats from outside the cabinet.
Paroubek aimed to reassure voters that a leftist government would not be too radical, saying it might include independent experts to the right of the Social Democrat platform.
He did, however, all but rule out co-operation with Miroslav Kalousek, leader of the Christian Democrats, his current junior coalition partner. Paroubek has clashed with Kalousek several times and has said he is not trustworthy.
Paroubek said that over the next half year he would try to push through as much of his party's leftist agenda as possible.
Parliament is currently debating tax cuts aimed squarely at low and medium earners, and a new labour code that strengthens the role of unions.