McConnell, R-Ky., negotiated what he called an "imperfect solution" with Vice President Joe Biden to avert the country from going over the "fiscal cliff" of increased taxes and across-the-board spending cuts.
President Obama signed the American Taxpayer Relief Act of 2012 Wednesday while he was in Hawaii with his family. The law makes permanent lower tax rates passed during President George W. Bush's administration on income up to $400,000 for individuals and $450,000 for families; permanently indexes the Alternative Minimum Tax exemption amount to the Consumer Price Index; extends emergency unemployment benefits for one year; continues existing Medicare payment rates for physician services through Dec. 31; extends farm bill policies and programs through Sept. 30, and delays automatic, across-the-board federal spending cuts for two months.
Income above $400,000 (individual) and $450,000 (couple) will be taxed at the rate of 39.6 percent, which was effect when President Clinton was in office.
"[Now] that the president has gotten his long-sought tax hike on the 'rich,' we can finally turn squarely toward the real problem, which is spending," McConnell wrote in a commentary published by Yahoo! Wednesday.
"The first day of a new Congress always represents a fresh start," the Republican from Kentucky wrote. This year, it also presents a perfect opportunity to tackle the single-greatest challenge facing our nation: reining in the out-of-control federal spending that threatens to permanently alter our economy and dim the prospects and opportunities of future generations of Americans."
He said the deal shielded more than 99 percent of taxpayers from a massive tax hike "that President Obama was all-too willing to impose."
McConnell said the debate on taxes "is over. Now the conversation turns to cutting spending on the government programs that are the real source of the nation's fiscal imbalance."
"And the upcoming debate on the debt limit is the perfect time to have that discussion," he said.
"The president may not want to have a fight about government spending over the next few months, but it's the fight he is going to have," McConnell said, urging Democrats to "deliver the same kind of bipartisan resolution to the spending problem we have now achieved on revenue."
The bill passed the Senate, 89-8, early New Year's Day and was approved by the House Tuesday night on a 257-167 vote after discussions were raised about whether to try to amend the bill to include more spending cuts.
Obama also signed the Defense bill, which authorizes Fiscal Year 2013 appropriations for Pentagon programs and military construction, Energy Department national security programs, and Transportation Department maritime security programs; authorizes recruitment and retention bonuses, special payments, and other authorities relating to the armed forces, and makes other modifications to national security, foreign affairs and other related programs.