Negotiations between unions and the U.S. Chamber of Commerce over a proposed temporary worker program to be part of immigration reform have hit some "bumps in the road" but are still ongoing, a top labor official said Wednesday.

Leaders from the pro-business Chamber and two of the country's largest labor groups -- the Service Employees International Union and the AFL-CIO -- have been tasked with hashing out an agreement over such a program, to be included in the Senate's immigration reform bill.

Temporary workers would fill seasonal jobs--anything from fruit picking to working as a housekeeper in a resort that's only open for part of the year--that business groups say are hard to fill with American workers. Unions helped kill the last immigration reform effort in 2007 over the inclusion of a guest worker program, which they worried would reduce wages and the compromise the influence of organized labor by providing employers with cheaper, non-union workers.

Several Senate Republicans who favor immigration reform have said a guest worker program must be included in the bill, even as President Barack Obama left out any mention of temporary workers in the broad immigration reform principles he released earlier this month.

The unions now say they would support a guest worker program if a commission of economic experts was able to set a cap on how many temporary workers could come in each year, based on economic conditions. Chamber officials are skeptical of this panel's power to set caps on the number of workers.

SEIU Secretary-Treasurer Eliseo Medina told Yahoo News that the negotiations have hit "bumps in the road" but that he still remains optimistic the two sides will eventually reach a resolution.

"I don’t think it’s any huge problem or that it endangers the process," Medina said.

On Wednesday, unnamed sources close to the negotiations told Politico that they predicted the talks would fail, as labor groups and the Chamber seemed to be no closer to finding common ground than when they began.

But Medina said representatives from the groups are meeting again tomorrow. "This is part of a process," he said of the disagreements. "There are some tough issues we’re talking about."

A spokeswoman for the Chamber, Blair Holmes, also said the groups are continuing to meet and still hope to reach a deal.

Read more: Yahoo! News