The Democratic presidential candidates are focused inward for the moment, talking to the voters who will participate in the primaries and caucuses next year. They are also looking at one another, doing their own cost-benefit analyses of whether to go on the attack against a rival or play their own game and let others fight.

That tension is what enlivened the second half of Thursday's Democratic debate in Los Angeles, when Sens. Elizabeth Warren of Massachusetts and Amy Klobuchar of Minnesota both went after South Bend, Indiana, Mayor Pete Buttigieg. Warren attacked him for taking money from rich people at fancy venues, including a wine cave in California; Klobuchar questioned his electability.

To Warren, fundraising at high-dollar events such as the ones Buttigieg attended is a symbol of how big money has polluted and corrupted politics. But Buttigieg called her attack hypocritical, saying she had raised money the very same way as a Senate candidate, only to swear it off as a presidential candidate. He noted, however, that some of that money had been transferred to her current campaign. "Did it corrupt you, senator?" he asked. "Of course not."

There will be more of this kind of debating over the next few months, as voters begin to be heard in Iowa and New Hampshire and elsewhere, and as the field of candidates begins to shrink to those who are able to amass delegates. The jockeying will intensify as this takes place.

But while the outcome of the Democratic Party nomination may be influenced by such pointed personal issues, the general election will turn on broader points. This is why a question about the economy posed in the first hour of Thursday's debate previewed the challenges the eventual Democratic nominee will face in the campaign against President Donald Trump.

PBS NewsHour's Judy Woodruff asked the candidates how they would appeal to voters who, while not being enthusiastic about Trump's conduct, do like the state of the economy, and thus might be reluctant to risk changing presidents.

The Democrats who answered Woodruff challenged the premise of the question instead of giving a direct answer.

"I don't think they really do like the economy," former Vice President Joe Biden responded. "The middle class is getting killed. The middle class is getting crushed. And the working class has no way up."

Buttigieg agreed. "The biggest problem in our economy is simple," he said. "People are not getting paid enough. That is not the result of some mysterious cosmic force. It's the result of bad policy. And we've got to change it by raising wages and empowering workers."

Warren said most Americans are not enjoying the fruits of the expanding economy and pointed to a corruption of the governing process as the cause. "When you see a government that works great for the wealthy and the well connected and for no one else, that is corruption, pure and simple," she said.

Sen. Bernie Sanders, I-Vt., agreed. "Today in America, we have the highest rate of childhood poverty of almost any major country on Earth, more income and wealth inequality than since the 1920s," he said. "We need an economy that works for working families, not just the 1 percent."

Andrew Yang, who often talks more creatively about the future economy than the other candidates, said there is very little connection between many of the economic statistics and the lives of most Americans. "GDP and corporate profits are at record highs in America today," he said. "Also at record highs? Depression, financial insecurity, student loan debt. . . . It has gotten so bad that our life expectancy as a country has declined for the last three years."

The responses from those on the debate stage represented standard Democratic critiques about the economy, focusing on the insecurity of many working families. The observations are not incorrect. The gap between the super wealthy and the rest of the country is large, and many families are struggling with the costs of health care or education, two tentpole issues for the Democrats.

A Brookings Institution analysis of a recent report from the Congressional Budget Office highlighted the degree to which middle-class incomes have not kept pace, growing more slowly than those at the top or even those below them. The outlook for the immediate future is better but overall not fast enough to catch up.

Many of those same conditions existed when Democrats last held the White House, and while the policies of the Obama administration helped bring the U.S. economy back after the 2008 financial collapse and put it on a growth path, they did not exactly alleviate the personal economic conditions that the presidential candidates cited on Thursday.

Trump may have inherited a growing economy from Barack Obama, but the economy has continued to grow during his tenure: Unemployment is at a half-century low; joblessness among minorities has continued to decline. The expansion that began in 2009 is now the longest in U.S. history. That is a record the Trump campaign will sell hard between now and November.

A few months ago, there were signs of trouble ahead for the economy. Today, those threats have lessened, though who can say with certainty where things will be a year or 18 months from now. Nonetheless, a new poll for CNN found that 76% of Americans rate the economy as very or somewhat good, up from a year ago and the highest recorded since February 2001.

One solution offered by the Democrats is higher taxes on the wealthy to produce revenue for investment elsewhere. Depending on the policies advocated, not just those in the top 1%, or even 10%, could see their taxes increase.

Some economists see risks in some ideas the Democrats are talking about. But when Warren was confronted Thursday with their statements saying her tax proposals could stifle economic growth, she dismissed their views: "Oh, they're just wrong," she said.

That ended the matter at Thursday's debate, but such glib answers will not end the debate during the general election.

Between incumbency and the statistical strength of the economy, Trump has, by historical standards, a real advantage in his bid for a second term. Democrats did not offer a clear counter to that on Thursday night. Whether they will need to do so is what makes 2020 potentially different.

The Democratic debate came a day after Democrats in the House impeached Trump for abuse of power and obstruction of Congress. The outcome in the Republican-led Senate seems preordained: acquittal by a party-line vote. But the whole impeachment proceeding has highlighted the real fault line in the electorate, which has so much to do with long-standing attitudes - good and bad - about the president.

The president's approval rating on the economy is far better than his overall approval rating. Which will be more determinative in the election? Will voters set aside positive views of the economy and vote against him because they find other aspects of his conduct reprehensible? Or will they set aside their negative views of him personally and vote to reelect him because they are satisfied with the economy and potentially worried about what would happen under a Democratic president?

What role the state of the economy will play is a big question heading into the election year. But thus far, Democrats are only offering partial answers.