A battle over gun ownership between President Barack Obama and the Republican-controlled U.S. Congress kicked off on Wednesday as lawmakers began weighing whether to fund the administration's unilateral moves to tighten background checks on buyers.

This month, Obama stirred conservative ire with executive action clarifying that all dealers selling guns, including at shows, flea markets, on the Internet or in stores, are required to get licenses and run background checks on buyers.

A Senate appropriations panel that funds Justice Department activities used its first hearing of the year to zero in on the new federal guidance that pits gun rights advocates against gun control organizations energized by a series of high-profile mass shootings.

U.S. Attorney General Loretta Lynch told the Republican-controlled panel the actions would "bring progress on a number of fronts" in the face of "an epidemic of gun violence."

In urging Congress to approve millions of additional dollars to help her agency hire more agents and conduct background checks around the clock, Lynch said she had "complete confidence" Obama's moves would survive any court challenges from opponents who argue he has over-stepped his authority.

But Senator Richard Shelby, the Republican chairman of an appropriations subcommittee, told Lynch the public fears Obama "is eager to strip them of their Second Amendment rights" to bear arms and warned that the panel "will have no part in undermining the Constitution and the rights it protects."

Obama issued his executive orders after Congress over the past few years refused to pass gun control legislation and as shooters carried out fatal attacks including on an elementary school in Connecticut, a movie theater in Colorado, a Virginia university and a community center in California.

Senior Democratic Senator Barbara Mikulski decried a "growing nexus of drugs, crime, guns, violence and murder" that she said resulted in more than 350 people being killed last year just in Baltimore, in her home state of Maryland.

Amid the infighting, Republican Senator James Lankford said there likely is common ground on the need for states to improve reporting to federal authorities on people convicted of crimes under state law.

"Alabama currently has zero felonies running into the (federal background check) system; California has 4,032. ... Delaware has zero, Maryland, 12, my fine state of Oklahoma has one," Lankford complained.

Congressional appropriators will spend much of this year wrangling over fiscal 2017 funding, such as money for gun background checks.

(Reporting by Richard Cowan; Editing by James Dalgleish)