Penn National Gaming is moving ahead with plans to expand a harness racing track into a slot parlor with dining and entertainment despite a looming vote on whether to repeal the 3-year-old Massachusetts casino law.

The company expects to spend more than $100 million and plans to have the shell of the casino building completed by November. In September, it will begin taking applications for about 500 permanent jobs at the parlor, located near the Rhode Island state line.

Supporters say the project will provide voters with a tangible example of the economic benefits of the casino law. Labor unions representing construction workers at the site promise to hammer home that message to voters in the coming weeks and months.