Yahoo and Google are trying to work with the U.S. Department of Justice to gain approval of their proposed advertising plan, according to a report in The Wall Street Journal.

The newspaper reported that the two companies are negotiating a deal that will curb concerns that the arrangement would concentrate too much power in the hands of Google.

The companies want to be able to place Google ads next to Yahoo search results and share the profits.

The Justice Department doesn't have to approve the deal, but it's investigating for potential anti-competitive impacts and could block the plan. The two companies recently postponed plans for their ad partnership because of the investigation.

Authorities in the European Union and Canada also are investigating the deal.

Consumers, businesses, and advocacy groups have complained that the arrangement would concentrate too much power in one place.

Competitor Microsoft claims that the partnership would send 90% of search ads to Google, which already dominates Web search and search ads. Advertisers have complained that the partnership could increase their costs.

Yahoo and Google have said they will continue to compete in the search market under the arrangement, and both companies have insisted the partnership is good for competition.

They had planned to launch the ad partnership in September, but the companies could risk interruptions and losses if the government imposed restrictions on them after the ad arrangement was under way.