allegations by Google critics that the company breaks antitrust laws by using its power in the market to smother competitors.
Many of the complaints are similar to assertions made by Gabriel Weinberg, a Massachusetts Institute of Technology graduate who started DuckDuckGo.com five years ago.
In an interview on Wednesday, Weinberg said it is difficult to make his DuckDuckGo the default search site in Google's Chrome web browser, and that Google disadvantages his company in the Android mobile operating system as well.
Google denies any wrongdoing and says it allows its users to choose alternative search engines across platforms.
Companies, including travel site operators and consumer reviews website Yelp, have accused Google of manipulating search results to steer traffic to Google products.
There have also been complaints about Google blocking access by rivals to its Android wireless phone operating system and about inappropriately asking for injunctions for infringing on standard essential patents, which ensure interoperability.
FTC commissioners are wrestling with whether they have enough evidence to file a complaint against Google on manipulating search results. But the agency is more confident that it could litigate the other issues, according to two people familiar with the FTC's deliberations.
Weinberg, who met with the FTC recently but declined to describe the talks, said that the Android wireless phone comes with Google as the phone's standard search mechanism.
DuckDuckGo can be added as an app to a mobile device, which is less convenient than being the default search engine, said Weinberg.
He also said his company had tried to buy the duck.com domain from its previous owner, On2 Technologies, but was rejected. Google eventually acquired the domain when it bought the entire company, and redirects duck.com traffic to Google.com.
"It only started redirecting after we inquired about (buying the domain name)," said Weinberg. "It causes confusion."
A Google spokeswoman said the company acquired On2 in 2010 and then pointed duck.com to Google's homepage, "just as we have for many domains we've gotten through acquisitions."
Weinberg told Reuters that Google's Chrome browser also made it difficult to change the instant search feature at the top of the browser to DuckDuckGo.
"It's one-click to get onto Firefox and it's five steps on Chrome and people generally fail," he said.
The Google spokeswoman said popular search alternatives were offered on its Chrome browser in a dropdown menu, such as Yahoo and Microsoft's Bing, but any search engine could be easily added.
A former antitrust enforcer, who asked not to be named, said the actions that Weinberg complained about were unexciting taken individually but, as a cluster, could be worrisome.
"It's relevant. It's what antitrust enforcers call monopoly soup," said the enforcer.