What is the reason for the fact that at first the industrial bourgeoisie led the struggle for parliamentary reform

What is the reason for the fact that at first the industrial bourgeoisie led the struggle for parliamentary reform, and then (at the stage of Chartism) the workers became the main support of this struggle?

The industrial bourgeoisie was very unhappy with the fact that it was actually removed from the management of state affairs, which did not correspond at all to the role it played in the life of society. And the parliamentarians went to meet them, partially meeting their demands. But since the workers and the petty bourgeoisie (they were the majority) remained deprived of the right to vote due to property restrictions, the reform gradually, thanks to them, acquired a nationwide character, where the main support, of course, was the workers.