She also says a Social Democrat-led government would raise the maximum level of unemployment benefit from $93 to $131 per day. She says she would also be prepared to legislate to give part-time workers the right to go up to full-time work.
Sahlin says the extra money to pay for her reforms will come from higher taxes, and removing the current centre-right government's "unfair" tax cuts, according to news agency TT.
She used much of her speech to attack Prime Minister Fredrik Reinfeldt, accusing him of failing to create jobs and shutting people out of society.
Finance Minister Anders Borg told TT he would wait until Monday to respond to Sahlin's criticism, on Monday the Social Democrats, Left and Green parties will present their joint shadow budget.
Left Party Leader Lars Ohly, also part of the red-green opposition, which would form a coalition government if elected in September, says a red-green government would also invest in rental accommodation. They would spend $200 million to build new council homes, and another $550 million to renovate the current council house stock.
May Day, or Labour Day, used to be an important event for many Swedes, but has recently waned in importance, despite still being a public holiday. It's estimated that around 6000 marchers took part in this year's demonstration in Stockholm.
Meanwhile, in the southern town of Helsingborg, a group of Neo-Nazis held a demonstration. There were fears of clashes between the group and rival anti-fascists, and tensions were high but the two groups were kept away from each other, according to police.