ROME — In Naples, demonstrators blocked traffic. In Padua, Pisa and Milan, they clashed with the police. Here, they lobbed eggs at government buildings and climbed to the top of the Colosseum to unfurl a protest banner.

While their grievances are many, much of what has propelled Italians into the streets by the tens of thousands in recent weeks is the mere hint of a change to labor laws that, among other things, would make it easier for businesses to get rid of workers.

No matter that the law, known as the Jobs Act, has yet to be fully written, or that many economists consider it inadequate to solving the problems of Italy’s economy, which continues to stumble through recession.

On Tuesday, after weeks of protests that have become an ever-clearer gauge of the obstacles confronting Prime Minister Matteo Renzi, lawmakers were already considering proposals to water down the plan.