Faced with deep divisions within the Republican party, the White House and some conservative groups are targeting red-state Democrats in hopes of winning support for a sweeping rewrite of the nation's tax code and salvaging their economic agenda. White House legislative director Marc Short told reporters Monday that he is making the case for tax reform to Democratic lawmakers in the Upper Midwest and from states with strong manufacturing industries, such as Pennsylvania. Americans For Prosperity President Tim Phillips said his group, a conservative advocacy shop funded by the billionaire Koch brothers, will pressure Democratic Sen. Joe Donnelly of Indiana. Its sister group, Freedom Partners, has called out West Virginia Democratic Sen. Joe Manchin for previously supporting lower tax rates. The strategy is an acknowledgement that Republicans' fractious caucus has been unable to reach consensus on key issues—most notably the long-sought effort to repeal and replace Obamacare—but also the budget and raising the debt ceiling. In the House, Short said he has met with the centrist Blue Dog Democrats and the Problem Solvers Caucus, which is spearheading a bipartisan health care bill. Even in the Senate, where Republicans only need a simple majority to pass tax reform using special parliamentary rules, victory is far from guaranteed. Republicans hold a narrow control of just 52 seats, turning the backing of just one or two Democrats into a possible game-changer. "We've learned how difficult it is to thread the needle with 52 senators," Short said at an tax reform event Monday sponsored by the Koch groups.

"Unrig the Economy"

Even the event's theme—"Unrig the Economy"—mirrored language that Democrats have been using as they roll out their platform for 2018. On Tuesday, Senate Minority Leader Chuck Schumer outlined the party's priorities in any rewrite of the tax code in a letter to the White House and GOP leadership that was signed by all but three Democratic senators, Donnelly, Manchin and Heidi Heitkamp of North Dakota, all of whom hail from red states and are up for re-election next year. "Senator Heitkamp is approaching tax reform with an open mind, and she wants work across the aisle to help make reforms that will grow the economy and support working families," a spokesperson said.

Sen. Joe Donnelly, D-Ind. Tom Williams | CQ Roll Call | Getty Images

An aide to Donnelly said he supports a bipartisan process for tax reform and is "ready to exchange ideas with others in Congress and the Trump administration." Manchin did not return a request for comment. Democrats were united in opposing the health care bill, which not only would have left millions without insurance but was also viewed as an attack on one of President Obama's signature achievements. Tax reform does not carry the same political symbolism, however. Holding the line could test the strength of Democratic leadership.

"No one's afraid..."

Schumer's letter listed three requirements for cooperation on tax reform: preventing a tax hike on the middle-class, passing legislation through regular order rather than special rules known as reconciliation and ensuring that tax cuts do not add to the deficit. "We are confident that, by working together, we could modernize our tax system to increase working families' wages, improve middle-class job growth, promote domestic investment, modernize our outdated business and international tax systems and put in place sound fiscal policy that raises the revenue needed to meet the needs of our country," the letter states. Jim Manley, a former top aide to Sen. Harry Reid, said the bar for winning over any members of the other party is high—even for the letter's holdouts. The chaos surrounding the Trump administration has chipped away at the president's leverage, he said, making it harder for Republicans to woo red-state Democrats. "No one's afraid of the guy anymore. No one sees the need to try to cut deals with him," Manley said. "No one's afraid of getting on the wrong side of a Trump tweet storm anymore."

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