CHICAGO — Hillary Rodham Clinton’s presidential campaign will center on boosting economic security for the middle class and expanding opportunities for working families, while casting the former senator and secretary of state as a “tenacious fighter” able to get results, two senior advisers said Saturday.

They provided the first preview of the message that Clinton planned to convey when she launches her long-anticipated campaign on Sunday with an online video. Until now, the former first lady has offered only hints of what would drive her if she were to run a second time for the White House.

Clinton, who lost the 2008 nomination to Barack Obama, will skip a flashy kickoff rally in favor of conversations with voters about the economic needs of middle class families and the next generation.

Clinton appears unlikely to face a formidable primary opponent, though a handful of lower-profile Democrats such as former Maryland Gov. Martin O’Malley have said they are considering campaigns.

Should she win the nomination, Clinton would face the winner of a Republican primary field that could feature as many as two dozen candidates. Sens. Rand Paul of Kentucky and Ted Cruz of Texas have already entered the race. Sen. Marco Rubio of Florida is expected to announce his candidacy in Miami on Monday, and former Florida Gov. Jeb Bush, the brother and son of former presidents, is also likely to run.

The strategy described by Clinton’s advisers has echoes of Obama’s successful 2012 re-election campaign. He framed the choice for voters as between Democrats focused on the middle class and Republicans wanting to protect the wealthy and return to policies that led to the 2008 economic collapse.

The advisers said Clinton will argue that voters have a similar choice in 2016. Clinton also intends to sell herself as being able to work with Congress, businesses and world leaders.

That approach could be perceived as a critique of Obama. He has largely been unable to fulfill his pledge to end Washington’s intense partisanship and found much of his presidency stymied by gridlock within Congress.

The Clinton advisers spoke on condition of anonymity in order to discuss her plans ahead of Sunday’s announcement. People familiar with the plans say Clinton will travel to Iowa and other early-voting states to hold small events with residents in the days after the video’s release. By campaigning heavily in the early-voting states, which influence the rest of the state-by-state battle for party nominations, Clinton hopes to avoid making the same stumbles she did in 2008, when she entered the race as a U.S. senator and a heavy favorite only to be upset by Obama in Iowa’s lead-off caucuses.

In New York on Saturday, at the final event put on by “Ready for Hillary,” a group not connected with her campaign that’s worked for the past few years to stoke excitement for it, enthusiastic supporters joined elected officials and local party leaders to celebrate the launch to come.

As her official announcement loomed, the Republican National Committee linked Clinton to Obama, a regular focus of criticism from Republicans. “All Hillary Clinton is offering is a continuation of the same big government ideas that have grown Washington instead of the middle class,” RNC spokesman Michael Short said in a statement. “That’s why voters want fresh leadership and a new direction, not four more years of Obama’s failed policies.”

Clinton is not expected to roll out detailed policy positions in the first weeks of her campaign. Advisers said she planned to talk about ways families can increase take-home pay, the importance of expanding early childhood education and making higher education more affordable.

It’s not yet clear whether that will include a noticeable break with Obama on economic policy. Republicans have hammered Obama’s approach as anti-business and insufficient in the wake of the recession. The White House says the economy has improved significantly in recent years.

(AP)