Sometimes, politics is all in the packaging, and who's doing the talking.

On Monday, Ivanka Trump hit the road to promote the child-care aspect of the Republican tax-reform plan. Specifically, she's pushing for a big increase in the current $1,000 per child federal income tax credit.

Nice idea. Wrong salesperson.

This is a familiar theme for the Trump team when it comes to working the court of public opinion:

After winning the presidential election and stunning almost all the experts, perhaps President Donald Trump and the rest of his administration felt they could easily win the battle to pass controversial legislation despite a very slim Republican majority in Congress.

But the Obamacare repeal and replace failure proved that campaigning for bills mostly on Twitter doesn't work.

Trump himself has been leading the way on tax reform, talking it up on the road at rallies and in TV interviews nearly every day.

But again, it's all still relative. President Trump is right to talk about tax reform as much as he is, but he's still using generalities and the kind of grand end-result promises we've heard from him since he was plugging Atlantic City casinos. We're hearing a lot of extreme selling points like "biggest tax cut in U.S. history" and touting the bipartisan effort.

That kind of talk might be good for re-election campaign ads, but while the tax-reform legislation is still in limbo, the key to success will be to talk more about household issues and focus on how the extra money President Trump is promising could be used. He needs to use terms and phrases like, "dining out a few more times a month," "buy a new washer and dryer," and "save for a family vacation" in the same way JFK and even George W. Bush successfully pushed for tax cuts or rebates in the past.

And while he should do this, the administration needs to button up a number of people acting as spokespeople for the plan that aren't really able to make the case from a middle class perspective. Treasury Steven Mnuchin, with his Wall Street pedigree with a side of Hollywood success, isn't the right guy to do this. Of course his job makes it imperative for him to work on the details of the tax plan and even privately lobby members of Congress. But national TV interviews are not where someone with Mnuchin's background and demeanor are going to shine.

And first daughter Ivanka Trump isn't right for the job either. No matter how hard she's worked, she remains a major symbol of inherited wealth and power that is millions of rhetorical miles away from the issue of child-care costs for working mothers and families. Her best role for the Trump team is humanizing her father as at least a person good enough to raise successful and nice children. Hey, even Hillary Clinton said it herself during the campaign — that she was most impressed with then-candidate Trump's kids and how they've been raised.

But there's a giant leap from there to being able to relate to working moms or make a strong policy argument on tax credits. Yes it's true that President Trump is a child of privilege himself, but he's been such a fighter for so long the he exudes a sense of urgency and a scrappy attitude that clearly endears him to the middle class and blue collar America. Ivanka will never be able to do that.

And, furthermore, she's not emotionally charged or charging speaker. Here's what she had to say Monday on the road:

"Every parent has to manage the competing demands of raising a family and their passions, whether it be professional or otherwise, and I, too, had to manage that, but I'm far more fortunate than most and I had help. I wouldn't be able to do even a small fraction of what I was doing professionally or as a parent, just being so tired and over-tasked, if I didn't have access to the means to be able to put myself my children in a secure and safe and protected and nurturing environment."

All of the above was factually true, and it was right for Ms. Trump to acknowledge her good fortune. But acknowledging your privilege doesn't help you connect with people — it just reminds them of it.

You know who would be good for the job — White House Office of Management and Budget, (OMB) Director Mick Mulvaney. He is a fantastic pitchman with his ease in front of the camera and assertive speaking style. In fact, he might be the best communicator in the entire administration.

The simple rule the Trump team must follow is this: Unless the spokesperson is as well-versed and good on camera as someone like Mulvaney, no rich person or presidential relative should be pushing the tax-reform plan it's selling as a boon to the middle class.

Just because Ivanka Trump is a woman with children and has a personal following and fan base doesn't mean she'll connect with working middle-class moms. A better choice would be a working mom from, say, Wisconsin. That point about balance would've been made far better by a working Midwest mom. In fact, that working mom might not even have to give a speech. She could just stand on stage next to President Trump as he talks about her struggles and the struggles of working parents like her, in the same way he so effectively did with the families of Americans killed by undocumented immigrants during the 2016 campaign.

The Trump team very much needs to make this push more about Main Street and less about Wall Street. Ivanka Trump isn't Main Street — she's Park Avenue.

Trump needs to get a map and figure out who's on what street — and how we get there — before the car breaks down.

Commentary by Jake Novak, CNBC.com senior columnist. Follow him on Twitter @jakejakeny.

For more insight from CNBC contributors, follow @CNBCopinion on Twitter.