Most of the action is in federal courts where former President Donald Trump was able to appoint conservative judges.

The strategy harks back to what Democrats did during Trump's presidency, heading to court in New York, California, Maryland and other states where they were likely to receive a friendly reception. Even before that, Republicans were frequent filers during Barack Obama's White House years.

“This is something the Republicans have taken from the Democratic playbook, just as the Democrats had taken a lot of things from the Republican playbook during Trump's tenure,” said New York University law professor Sally Katzen, who served in the Clinton White House.

The legal action reflects GOP opposition to Biden initiatives, but it also is providing the attorneys general, many with higher political ambitions, to showcase their willingness to stand up to Biden and unabashedly side with Trump.

Missouri Attorney General Eric Schmitt, seeking the Republican nomination for U.S. Senate in 2022, brags in a TV ad that he is “on the conservative front line suing to stop the Biden administration's worst abuses.'' The main target of lawsuits filed so far have been executive orders issued by Biden. But several states also have sued over a provision of the USD 1.9 trillion COVID-19 rescue plan that prohibits states from using their share of federal money to reduce taxes.

Chris Carr, the Georgia attorney general and new chairman of the Republican Attorneys General Association, said he and his colleagues have been cast in this role because Democrats control both houses of Congress and the White House.

''We've got a situation where President Biden says, Look, I want to be more bipartisan in nature.' But then he turns around and has issued more executive orders in the beginning of a term than any president in modern history, I'm told,” Carr said.

“Our job is to ensure the rule of law is upheld. It's a natural tension we've seen throughout American history. How does the federal government stay in its lane?” he said.

It took only two days after Biden's inauguration for the first legal fight to erupt. Following the president's announcement of a 100-day pause in deportations, Texas Attorney General Ken Paxton went to court and won a court order against the halt.

Several other states have since followed with similar claims.

Just since the middle of March: — Texas, Montana and 19 other states filed suit in Texas to overturn Biden's cancellation of the contentious Keystone XL oil pipeline from Canada.

— Louisiana Attorney General Jeff Landry led 13 states in suing the administration to end a suspension of new oil and gas leases on federal land and water and to reschedule canceled sales of leases in the Gulf of Mexico, Alaska waters and western states.

— Missouri sued over the restriction on state tax cuts as a condition of receiving money from the huge COVID-19 bill.

Earlier in March, Schmitt led 12 states in a suit that claims the administration lacks the authority to take account of the social costs of climate change. The president said on Jan. 20 that federal agencies must account for damages caused by increased greenhouse gas emissions, including changes in farm productivity, human health and property damage from increased flood risk.

In at least two instances, Republicans are trying to get the Supreme Court involved to keep in place Trump policies that Biden is reviewing or has indicated he will reverse.

Paxton is leading a push to get the justices to reimpose the Trump-era immigration rule denying green cards to immigrants who use public benefits like food stamps. A federal court has blocked the policy nationwide and the Biden administration dropped the defense of it.

Ohio Attorney General Dave Yost is leading a 19-state effort to keep the court from dismissing a case over the Trump policy that bans family planning programs that receive federal funds from referring women for abortions.

The administration and medical groups that had challenged the policy agreed to dismiss the case because the Health and Human Services Department shortly will propose a new rule rescinding the ban on abortion referrals.

Paxton's predecessor was Greg Abbott, now the Texas governor. Abbott burnished his conservative credentials by frequently going to court over Obama initiatives. “I go into the office, I sue the federal government, and I go home,” he said in 2013, boasting then of having sued the administration 25 times.

By the middle of 2016, The Wall Street Journal counted at least 44 times that Texas went to court against the Obama administration.

The one thing that has changed since the last Democratic administration is that Trump was able to move appeals courts across the country to the right, adding six judges each to appeals courts that hear cases from Ohio and Texas and four to the court that includes Missouri. All three already leaned conservative.