Senate to vote on LGBT discrimination bill Esteban Roncancio and other protesters voice opposition to discrimination against LGBT Americans in Miami Beach, Florida, in June. The Senate is set to vote on a key procedural measure Monday afternoon President Barack Obama wrote a rare op-ed voicing his support The bill would outlaw workplace discrimination for LGBT workers NEW: House Speaker John Boehner said he will not support ENDA Washington (CNN) -- The Senate will take up an anti-discrimination bill to protect lesbian, gay, bisexual and transgender employees from workplace discrimination. The Senate is set to vote on a key procedural measure Monday afternoon. It's the first time the Senate has moved to take up a comprehensive form of the bill. The Employment Nondiscrimination Act, also known as ENDA, would provide the same protections for LGBT workers as are already guaranteed on the basis of race, gender and religion. It would no longer be lawful for employers to discriminate based on a person's "actual or perceived" sexual orientation. Proponents are championing the bill, pressuring opponents or those on the fence to come out in support. President Barack Obama wrote a rare op-ed in the Huffington Post in which he called job-site LGBT discrimination "offensive" and "wrong." "And it needs to stop, because in the United States of America, who you are and who you love should never be a fireable offense," the President wrote. The newest member of the Senate, New Jersey Democrat Cory Booker, who was sworn in last week after a special election, has made a passionate defense of ENDA on one of his oft-used methods of communication. Opinion: No one should be fired for being gay He said on Twitter he will support ENDA, "Absolutely, unequivocally, proudly with gusto & enthusiasm. I hope to make it my first 'co-sponsor.' The measure is coming up for a vote because of a recent wave of momentum in support of it. The bill gained the support of all Democrats and both independents who normally caucus with them, and two Republican co-sponsors: Sens. Mark Kirk of Illinois and Susan Collins of Maine. Sen. Dean Heller, R-Nevada, announced his support Monday morning, significantly increasing the chances the Senate will pass Monday's procedural key procedural vote. In his op-ed, the President put pressure on not only the Senate but the House of Representatives as well, where a vote is much more uncertain. "If more members of Congress step up, we can put an end to this form of discrimination once and for all," Obama wrote. The Republican-led House might be a major obstacle to ENDA's success; House Speaker John Boehner has already announced his opposition. "The speaker believes this legislation will increase frivolous litigation and cost American jobs, especially small-business jobs," spokesman Michael Steel said. And Rep. Eric Cantor, R-Virginia, the second ranking House Republican, refused to commit to bringing up the legislation. He said that he and fellow Republican leaders "will review it" if the Senate passes it. The conservative political organization Heritage Action put out a notice to all Republican lawmakers recommending a no vote. Its scorecards are threatening assessments of lawmakers who fear a primary challenger or are in need of the outside group's influx of campaign cash. Heritage Action says the bill "raises serious religious liberty concerns" and would "potentially discourage job creation." An exemption for religious organizations is included in the bill, but some want the religious protection extended to secular businesses, which ENDA proponents say would gut the entire bill. Employers with fewer than 15 employees would also be exempted from the law. Heads of major businesses have come out in support of the law, including Tim Cook, Apple's CEO, who wrote an op-ed Monday in the Wall Street Journal. "So long as the law remains silent on the workplace rights of gay and lesbian Americans, we as a nation are effectively consenting to discrimination against them," he wrote. We urge senators to support the Employment Nondiscrimination Act, and we challenge the House of Representatives to bring it to the floor for a vote. Twenty-one states currently have laws on the books protecting lesbian and gay workers from discrimination and 17 states protect transgender workers, according to the Human Rights Campaign. The federal statute would create protections in all states and the District of Columbia. Opinion: ENDA threatens free markets