If chosen at LO's yearly congress at the end of May, Thorwaldsson will replace Wanja Lundby-Wedin, who has served as head of LO since 2000.
"The congress is not until a few weeks from now. Nobody knows what will happen but it feels ver nice that the nominating committee has proposed this," Thorwaldsson, who currently serves as chairman for the Workers’ Educational Association, told Swedish Radio News on Friday.
With only weeks left until Lundby-Wedin's departure at the end of the month, the nominating committee was undecided until agreeing to back Thorwaldsson on Friday.
Thorwaldsson said he would prioritize unemployment if elected.
"Many of the 396 000 unemployed people in Sweden are Lo-members. We have to get better at creating proposals with modern solutions that can fight unemployment and bring the country back to full employment. We also have to overturn the trend, gain new members and be more active in the debate," Thorwaldsson said.
LO has been suffering a loss of members in recent years. In 2011, LO had approximately 1.5 million members.