Outgoing Attorney General Eric Holder admitted he suspects some of the struggles he has had with Republican lawmakers over his more than six-years as the nation's top law enforcement officer were at least partly driven by race.

In a far-reaching interview aimed at crystallizing his tenure, 64-year-old Holder told Politico, "There have been times when I thought that's at least part of it. I think that the primary motivator has probably been political in nature. ... [But] you can't let it deflect from you."

As one of his final acts in office, Holder said he plans to spend the coming weeks pushing for a new standard for civil-rights offenses stemming from such cases as the shooting deaths of Trayvon Martin and Michael Brown, adding he's convinced such a change would make the federal government "a better backdrop" in such instances.

Self-appointed Florida neighborhood watchman George Zimmerman was found not guilty in the shooting death of the 17-year-old Treyvon, and a grand jury in Ferguson, Missouri, declined to indict police officer Darrren Wilson in the shooting death of Mike, also 17. Both teens were unarmed at the time of their deaths, and their killings and noncriminal findings against those involved sparked outrage and protest around the country.

"I think some serious consideration needs to be given to the standard of proof that has to be met before federal involvement is appropriate," Holder said.

"I think that if we adjust those standards, we can make the federal government a better backstop – make us more a part of the process in an appropriate way to reassure the American people that decisions are made by people who are really disinterested. I think that if we make those adjustments, we will have that capacity."

The Justice Department has already announced it will not be bringing federal charges against Zimmerman, and the probe against Wilson is rumored to be in its final days with the overriding consensus being he too will escape federal charges.

Throughout his tenure, Holder has faced heavy criticism from the GOP, including being voted in contempt of Congress by House Republicans in 2012.

In time, Holder said he hopes to one day work with a university or think tank in setting up an Eric Holder Institute for Race and Justice.