Attorneys general from Alaska, Arkansas, Iowa, Missouri, Montana, Nebraska, New Hampshire, North Dakota, South Dakota and Wyoming signed on to one lawsuit, which was filed in a federal district court in Missouri on Friday.

Another group of states - Alabama, Georgia, Idaho, Kansas, South Carolina, Utah and West Virginia - filed a separate lawsuit in federal district court in Georgia.

Texas sued individually on Friday, while Florida launched action on Thursday, meaning the mandate is being challenged by a total of 19 states across four federal courts.

The states have asked a federal judge to block Biden's requirement that all employees of federal contractors be vaccinated against COVID-19 by December 8, arguing the mandate violates federal procurement law and is an overreach of federal power.

"If the federal government attempts to unconstitutionally exert its will and force federal contractors to mandate vaccinations, the workforce and businesses could be decimated, further exacerbating the supply chain and workforce crises," Missouri Attorney General Eric Schmitt, a Republican, said in a statement.

"The federal government should not be mandating vaccinations, and that's why we filed suit today - to halt this illegal, unconstitutional action."

New Hampshire's Republican Attorney General John Formella said in a statement that COVID-19 vaccines are safe, effective and encouraged but that the benefits "do not justify violating the law".

Biden has argued sweeping vaccine mandates will help end the deadly pandemic, but Republicans nationwide have opposed the requirements and have threatened to bring similar legal challenges.

"The Biden Administration has repeatedly expressed its disdain for Americans who choose not to get a vaccine, and it has committed repeated and abusive federal overreach to force upon Americans something they do not want," said Texas Attorney General Ken Paxton in a statement.

"The federal government does not have the ability to strip individuals of their choice to get a vaccine or not.

"If the President thinks his patience is wearing thin, he is clearly underestimating the lack of patience from Texans whose rights he is infringing."

A number of states have also said they will challenge Biden's plan to have the US Occupational Safety and Health Administration issue a rule that would mandate vaccines for all private businesses with 100 or more employees.

"We will not allow the Biden administration to circumvent the law or force hardworking Georgians to choose between their livelihood or this vaccine," Georgia's Republican Governor Brian Kemp said in a statement.

The Democratic Party of Georgia called the lawsuit a "dangerous political stunt".

All but two of the states that have sued trail the national average vaccination rate. Only New Hampshire and Florida exceed the nationwide rate.

Australian Associated Press