Swedish left bloc failed to garner a support enough for a majority in Sunday's general elections forcing them to search for ways to form a "cross-bloc" cooperation.
The ruling Social Democrats got 40.6 percent of the votes, barely ahead of the center-right Alliance, which claimed 40.3 percent in the polls, according to unofficial results.
Left bloc parties will have 144 seats while right bloc parties will have 143, which hints talks negotiations ahead to form a government.
Sunday's polls also saw far-right, anti-immigrant Sweden Democrats (SD) boost their vote rate to 17.6 percent from 12 percent in 2014, making them the third biggest party in Sweden.
SD will have 62 seats in the parliament.
Swedish national public TV channel SVT said on Monday that 99 percent of the ballot boxes were opened.
A number of 7.5 million Swedish electors went to polls on Sunday.
For an absolute majority, a bloc should have 175 seats in the 349-seated Swedish Parliament.
Swedish Moderate Party leader Ulf Kristersson called PM Lofven to resign.
However, Lofven said that they were the winners of the elections. "I will not resign, we have right to form the new government", he said.
Sweden Democrats leader Jimmie Akesson said that they were the only winners of the elections, calling the right bloc to make a coalition.
Right bloc parties have said earlier they would certainly not form a coalition with the SD.