The biggest roadblock for Trump's tax plan could be Trump himself

Republicans are trying to finalize their tax proposal.
Trump's tweets on 401(k) savings and attacking GOP Sen. Bob Corker could be a signal of things to come.
Adding a volatile presidential social media account to the already difficult process of rewriting the tax code could endanger the whole effort.

Republicans attempting to come together on a massive overhaul of the federal tax code are facing a novel roadblock along the way: the president's Twitter account.

Another example of the unpredictable nature of President Donald Trump's role in the tax reform push came Tuesday, as the president once again attacked Sen. Bob Corker, a key tax reform figure, via Twitter.

"Bob Corker, who helped President O give us the bad Iran Deal & couldn't get elected dog catcher in Tennessee, is now fighting Tax Cuts,"Trump tweeted. "Corker dropped out of the race in Tennessee when I refused to endorse him, and now is only negative on anything Trump. Look at his record!"

The tweets also came after Corker criticized Trump and his administration's approach to tax negotiations on NBC's "Today" show and on ABC's "Good Morning America."

"Tax writing committees in the Senate and the House are going to be laying out the $4 trillion in loophole closings that need to take place," Corker said on NBC. "Hopefully the White House will step aside and let that occur in a normal process."

Corker also followed up in an interview with CNN, after Trump had initially responded, saying that he would not support the president in an election going forward and that Trump will be remembered for "the debasement of our nation."

Isaac Boltansky, a policy analyst at the research firm Compass Point, said Trump is doing himself no favors on tax reform by fighting Corker.

The attacks on a key senator also come the day after Trump undermined a possible legislative option for the tax plan regarding retirement savings on Twitter.

"There will be NO change to your 401(k)," Trump tweeted Monday. "This has always been a great and popular middle class tax break that works, and it stays!"

The proclamation came just a few days after reports surfaced that Republican leaders in the House were considering a cap on traditional, tax-deferred 401(k) and IRA retirement accounts as a way to generate revenue and pay for the plan under budget rules.

How serious Republicans were about the idea is unclear, but Trump's tweets cut off any discussion.

It was not the first time that the president's whims of the president have thrown a wrench into the tax plans.

In the days before the release of the so-called Big Six's framework, Trump said the wealthiest Americans would not benefit from the tax plan and could even see their taxes increase.

That led to a scramble to include provisions to satisfy Trump's edict — including the option for a fourth, top tax bracket to be added to the plan. Then, after House Speaker Paul Ryan said Friday that the fourth tax bracket would likely be added, Trump told Fox Business that he doesn't want a fourth bracket if it can be avoided.

According to a report from The New York Times, Republicans and lobbyists involved on the tax plan are concerned about the possibility of Trump swaying on various elements of the plan. Republican Rep. Charlie Dent told the Times that Trump "can shift on a dime" and the GOP has to "worry about him shifting positions."

Krueger said Trump's tweets leave tax negotiators in the same limbo as the bipartisan group attempting to fix the Affordable Care Act.

"This was very likely not coordinated with congressional tax writers who are in a similar purgatory to Senate Republicans who floated their CSR proposal only to see Trump oppose it (these kind of reactions are only going to increase as Congressional tax plans seek to gore every sacred cow in the code)," Krueger wrote in a note to clients Tuesday.

The constant changes and Twitter attacks by Trump are not unprecedented for a major legislative push.

When Republicans were pushing a healthcare overhaul, Trump hosted a White House Rose Garden ceremony to celebrate passage of the House's healthcare bill. Weeks later, he called the same bill "mean." Later, when the Senate was debating various legislative options to repeal and replace Obamacare, Trump attacked various holdouts of the Senate bill on Twitter.

That effort was eventually shelved.