Hillary Clinton accused her opponent for the Democratic nomination on Wednesday of advancing vague and unrealistic policy proposals as the two campaigned in Philadelphia.

After suffering a 13-point loss in Tuesday's Wisconsin primary, the former secretary of state took direct aim at Sen. Bernie Sanders, suggesting he has not thought through how to implement his promises.

"Like a lot of people, I am concerned that some of his ideas just won't work because the numbers don't add up," Clinton told hundreds of members of the Pennsylvania AFL-CIO, meeting in their annual convention in Center City.

"Others won't even pass Congress, or they rely on Republican governors suddenly having a conversion experience and becoming progressives," Clinton said with a hint of sarcasm. "In a number of important areas, he doesn't have a plan at all."

Sanders campaigns on promises of single-payer health care, free tuition at public universities and colleges, and an end to unfair trade agreements, among other things.

When he was campaigning in Wisconsin, a large industrial state like Pennsylvania, Sanders hammered Clinton for the enactment of the North American Free Trade Agreement during her husband's administration in the 1990s, and for her support of other trade deals that he says cost jobs.

Clinton warned the AFL-CIO members here against "distortions" of her trade record that she said they will hear leading up to the April 26 Pennsylvania primary. She said she voted against the Central America Free Trade Agreement as a U.S. senator from New York, and opposes the pending Trans Pacific Partnership - after having helped negotiate it as secretary of state in the Obama administration.

In her half-hour speech, occasionally interrupted by applause, Clinton pledged to stop China from "taking advantage of our workers and markets" by currency manipulation and "dumping" cheap products such as steel in the U.S.

"I will stop dead in its tracks any trade deal that hurts America," Clinton promised. If she wins, she said, "organized labor will always have a champion in the White House and a seat at the table."

Clinton has been endorsed by 25 national unions, including the Service Employees International Union, AFSCME, which represents government workers; the American Federation of Teachers; and the United Food and Commercial Workers.

Sanders has been endorsed by the Communications Workers of America, the American Postal Workers Union, and National Nurses United.

Earlier Wednesday, in an appearance on MSNBC, Clinton highlighted an interview Sanders gave recently to the New York Daily News in which he could not answer specific questions about how he would carry out his promises to break up big banks.

"You can't really help people if you don't know how to do what you are campaigning on saying you want to do," she said. "He hadn't done his homework and he'd been talking for more than a year about doing things that he obviously hadn't really studied or understood."

After her appearance at the union gathering, Clinton stopped in to visit young ex-offenders working on their resumés at Impact Services Corp., a Kensington nonprofit that teaches job skills and links people in need to employment opportunities, houses homeless veterans, and works on economic-development projects in the neighborhood, one of the poorest areas of the city.

Clinton said she would increase federal support by $5 billion for training, counseling, and housing programs like those at Impact Services, in conjunction with $125 billion to create jobs by fixing roads, bridges, and other infrastructure.

"There are a lot of folks who need some mentoring, need some support, need some guidance, need some skills - but who have an enormous amount of talent, energy, and willingness to contribute," Clinton said.

She was heading to Pittsburgh for more campaign stops at the end of the day. But a Clinton will be here again Thursday: Her husband, Bill, will be in Philadelphia at lunchtime to lead a rally on her behalf.

With the Wisconsin victory, Sanders has now won six of the last seven contests against Clinton. His streak has raised some concerns among Democrats about Clinton's vulnerabilities, including persistent voter doubts about her honesty and trustworthiness as expressed in public opinion polls.

That's a long-term challenge as Clinton seeks to energize the Democratic base to support her in the fall. In Wisconsin exit polls, six of 10 Democratic primary voters said they found her to be honest and trustworthy.

In those exit polls, Sanders ran even with Clinton for support among women, who have buoyed her in other races. He won among both higher- and lower-income voters, including union households, and broke even with her among moderates.

Still, Sanders' relative success has not made a significant dent in Clinton's lead in delegates, the metric that counts the most in winning the Democratic nomination. Since the party allocates delegates in proportion to a candidates' votes in primaries and caucuses, that makes it difficult for underdogs to make up ground.

The Vermont senator would need to score massive victories in New York, Pennsylvania, and other states yet to vote to have a realistic chance.

In an interview with Politico for a podcast, posted earlier Wednesday, Clinton said, "I'm not even sure he's a Democrat" when asked about Sanders. He serves in the Senate as an independent and describes himself as a democratic socialist.