Quiz: These are all quotes from a prominent economist who has long advised presidential campaigns. Does he sound like he's now working for Hillary Clinton or Jeb Bush?

*"I don’t think you can have sustainable, high-production GDP growth without broadly shared prosperity"

*"The highest marginal tax rates are not paid by the rich. They’re paid by many of the working poor."

*“We have to make sure that anybody who’s willing to work full time shouldn’t be poor.”

As you've probably guessed, this is a trick question. It's actually a double trick. The economist is Glenn Hubbard, the dean of Columbia University's business school, the former top economist for President George W. Bush and a 2012 adviser to GOP presidential nominee Mitt Romney. The first trick is that Hubbard, in a half-hour discussion in his office, often talked about the U.S. economy in terms favored by far more liberal economists, including those on Clinton's team.

The second is that Hubbard still won't say whether he's working for Jeb Bush this cycle, even though it's widely agreed in economic circles that he is. He won't rule out talking to other candidates - including the Democratic frontrunner.

“I’ll talk to anybody who will ask me for advice," Hubbard said in his campus office, where a framed copy of the annual Economic Report of the President hangs on a far wall. "I’m hoping Mrs. Clinton will, but she hasn’t asked me yet.”

Much of the advice Hubbard dispenses these days is about how to reorient economic policy to unleash faster economic growth -- and to help ensure the benefits of that growth are more widely shared among workers. On the growth point, he echoes a lot of conservative economists, and conservative candidates such as, well, Bush, who has set a goal of fostering 4 percent annual growth as president.

Hubbard defended Bush's goal in a Wall Street Journal op-ed this week, co-written with Stanford's Kevin Warsh. (Many economics writers have questioned whether such growth is feasible given current economic trends.) In the interview last week, Hubbard said it was clear America could and should be growing faster than it is, but he was careful to avoid predicting that the economy could actually grow at 4 percent a year under a hypothetical Bush presidency.

“You’re making a case about an aspiration and then trying to outline policies you think will get you to that aspiration. But I don’t know enough – I can’t tell the future to say if we’re going to be able to get to that aspiration," he said. “But to me the debate should be, do you think there's secular stagnation and we’re just going to have to live with 2 percent (growth), or are we going to be able to live with some higher number? Whether it’s 4 percent or some other number – that’s the debate.”

Hubbard believes that for too long, the United States has only experienced rapid growth in the midst of what he calls "bubble economies," which don't deliver broadly shared prosperity to workers. For example, he blames the Federal Reserve for stoking a bubble in the mid-2000s by keeping interest rates too low for too long. Hubbard was a key economic policymaker in that time, in the George W. Bush White House, and I asked him why the tax cuts and other policies he helped craft then didn't spark more non-bubble growth. He blamed outside events.

“If you look at the whole decade of the 2000s, many shocks happened – in terms of foreign policy, in terms of shocks to the investment climate, accounting scandals, monetary policy issues," he said. "There were solid effects of tax policy in that period, but they were overwhelmed by other factors. If we’re going to see broadly shared prosperity for a longer period of time, we’re going to need to click on more cylinders than we did then – trade, regulatory, tax, spending reform, broadly speaking government reform.”

Which brings us to Hubbard's prescription for bubble-free, broadly shared growth today. It starts with the conservative stalwarts of lowering taxes - particularly the corporate tax rate - and reducing loopholes in the code; paring back federal regulations and tweaking safety net programs, such as Social Security, to encourage recipients to work more. It extends into more liberal waters: sending more money to supplement lower-wage workers, either through direct subsidies or an expanded Earned Income Tax Credit.

There's even a crucial break with other conservatives in Hubbard's tax-reform ideas. Many conservative economists, most notably supply side godfather Arthur Laffer, argue that reducing the marginal tax rate paid by the nation's top income earners is critical to accelerating growth. Hubbard said that, because of the structure of benefits under the Affordable Care Act and the phase-out of some tax credits, lower-income earners often face the highest marginal rates, so reform must help them, too.

"If we’re going to say that our thesis is very high marginal tax rates (holding back growth), why are we only talking about high-income people?" he said. "It should be across the board. It should be everybody. And particularly because, if we’re trying to encourage work, you really have to make work pay."

"We have to think more broadly in this country about shared prosperity," he added, at the close of the interview. "And the only way I know how to do that is through work.”

Shared prosperity, through work. That sounds like a good campaign message. For someone.

Jim Tankersley covers economic policy for The Washington Post. This article appeared on June 23, 2015.