Republicans renewed their calls to delay or repeal ObamaCare Monday after the Obama administration announced another delay in the requirement for businesses to provide health coverage to workers, giving some employers a reprieve next year while phasing in the mandate for others.

The administration had already delayed the implementation of the so-called employer mandate by a year, initially pushing the requirements off until 2015 -- past the midterm elections. In a concession to business, though, Treasury Department officials announced Monday that the administration would not enforce the rules across the board next year.

"Once again, the president is giving a break to corporations while individuals and families are still stuck under the mandates of his health care law. And, once again, the president is rewriting law on a whim," House Speaker John Boehner said in a statement. "If the administration doesn't believe employers can manage the burden of the law, how can struggling families be expected to?"

Sen. John Barrasso, R-Wyo., said the announcement Monday is only "further evidence that the health care law is hurting the economy."

As a result of the delay, the administration will let employers with 50 to 99 employees off the hook in 2015. They'll be required to report on how many workers are covered but will have until 2016 before being required to cover full-time staff or pay a penalty. Americans would still be required to obtain health insurance through what's known as the individual mandate.

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Under the changes, employers with 100 or more workers will be required to provide health insurance to full-time staff next year. However, the new rules will only require them to cover 70 percent of workers at first; and then 95 percent the following year and beyond.

As before, companies with fewer than 50 employees will not be required to provide health coverage.

The latest announcement comes after the administration heard from businesses about their concerns with the looming ObamaCare rules. However, the change is sure to raise more questions about the health and implementation of the law. Fewer workers getting insurance through their employers could mean more individuals on the ObamaCare exchanges seeking subsidized coverage, increasing the cost to taxpayers.

Some lawmakers, though, have claimed that the mere threat of the employer mandate is causing companies to shed full-time workers in the hope of keeping their staff size below 50 and avoiding the requirement.

Administration officials dispute that this is happening on any large scale. Further, Treasury officials said Monday that businesses will be told to "certify" that they are not shedding full-time workers simply to avoid the mandate. Officials said employers will be told to sign a "self-attestation" on their tax forms affirming this, under penalty of perjury.

Officials stressed that the latest reprieve applies to a relatively small percentage of employers -- albeit companies that employ millions of workers.

Separately, Barrasso joined Sen. Tom Coburn, R-Okla., and other Republican lawmakers in writing a letter to IRS Commissioner John Koskinen on Monday asking about the enforcement of the individual mandate, considering all the other changes to the law's implementation.

"Given a number of last-minute administrative 'adjustments' made by the Administration, there is some understandable confusion and concern about the enforcement of the individual mandate tax," they wrote. "With the Administration's decision to waive, delay, or unilaterally alter some provisions of the law-including the employer mandate tax on businesses-taxpayers deserve clarification on how the agency intends to enforce the individual mandate tax."