These are challenging days for America and most Americans. Years of tough times have led to millions of people losing their jobs, homes, health care or pensions. Huge inequalities in our economy and society have been exposed but not adequately addressed. The middle class is shrinking, poverty is growing and American optimism is often clouded by anxiety, uncertainty and fear.

In the midst of this, Americans will elect a president. This year’s election is a choice, not a referendum. It’s a choice between very different economic visions for our country, and at stake is the simple yet powerful notion that everyone deserves a fair chance to achieve the American dream.

The 1.5 million members of the American Federation of Teachers endorsed President Barack Obama this week because we know that he is the only candidate who will fight to preserve and expand the middle class and fight for economic opportunity for all Americans.

Obama is the only candidate who understands that there is something fundamentally wrong with an economic system that allows the top 1 percent of Americans to hold nearly half the country’s wealth. He understands that we can’t rebuild the middle class when one in four households and an astounding 40 percent of Black households have zero or negative net wealth.

Despite stiff opposition from Republicans in Congress, Obama continues to fight to put Americans back to work, ensure that working people have a strong voice on the job, help Americans keep their homes, invest in our schools and repair our aging roads, bridges and decaying infrastructure.

This does not mean that AFT members agree with every decision that the president and his administration have made. In particular, we disagree strongly with elements of the administration’s education polices that appear to focus more on competition and measurement than on promoting what frontline educators know will improve teaching and learning. According to a recent poll, frontline educators in New York City are more trusted than the mayor to protect the interests of schoolchildren.

When we have disagreed with the Obama administration, the AFT has made that known, and we will continue to do so. Despite our disagreements, it’s significant that in his State of the Union address, Obama made clear that teaching to the test has no place in a robust education system and that higher education should not be a luxury.

The differences between Obama and the Republican candidates will define the nation’s choice on Nov. 6. The difference between a president who fought for legislation to make health care accessible to millions of Americans who otherwise would go without and opponents who seek to repeal it.

The difference between a president who has used his office to advocate for workers’ and union rights and opponents who have supported efforts to strip workers of their voice and their rights in Wisconsin, Ohio and elsewhere. The difference between a president who has worked to rebuild the middle class and who believes that “everyone should have a fair shot at success” and his opponents who put corporations and the wealthy above average Americans.

These are not minor differences. The candidates running for the Republican nomination are promoting a view of America that differs greatly from the one held by those of us concerned about economic and educational opportunity for all and about making sure everyone has a fair chance to achieve the American dream.