No candidate looms larger over the 2016 presidential race than the woman who made her entry into the campaign official on Sunday — Hillary Clinton. In stark contrast to the Republican field, where several candidates could fight through months of primaries to produce a frontrunner, Ms. Clinton faces no serious rival for the Democratic nomination.

That could change. In 2008, Ms. Clinton was also the strong favorite, few giving a freshman senator from Illinois, Barack Obama, much chance to seriously challenge for the Democratic nomination. Yet it is hard to envision former Maryland governor Martin O’Malley, the only rival so far of note, repeating the electrifying rise to political prominence that the nation witnessed with Mr. Obama.

Ms. Clinton’s experience is unmatched with eight years as a First Lady engaged on policy issues, two terms in the U.S. Senate from New York, four years as secretary of state.

A slick video Ms. Clinton released to announce her candidacy gave an inkling of where she intends to take her campaign. Most of the short video features Americans talking about their lives and hopes. Ms. Clinton appears at the end, noting, “Americans have fought their way back from tough economic times, but the deck is still stacked in favor of those at the top.”

As a candidate, expect Ms. Clinton to capitalize on the fact the economy has largely recovered under the fellow Democrat she hopes to replace, President Barack Obama. She will try to link her Republican rivals and their policies to the bad old days and the Great Recession of President George W. Bush.

Ms. Clinton also recognizes that in relative terms, middle-class incomes have declined and that wealth growth during the recovery has largely benefitted the rich.

“Every day Americans need a champion, and I want to be that champion, so you can do more than just get by. You can get ahead and stay ahead,” said Ms. Clinton.

The nation awaits the details. Her past centrist, deregulation market philosophy — championed by her husband, President Bill Clinton during his time in office — will not sit well with the party’s progressive wing. Meanwhile, the Clinton money machine, expected to generate upwards of $1 billion for a presidential race, will look to Wall Street.

Providing policies to restack the deck to help the working class, without coming across as anti-business, may be Ms. Clinton’s biggest challenge.