(CNN) - U.S. Sen. Scott Brown of Massachusetts rejected his party's draft language on abortion in a letter to the Republican National Committee chairman Tuesday.
In the letter, Brown expressed apprehension over "language opposing a woman's right to choose and supporting a constitutional amendment banning abortion."
– Follow the Ticker on Twitter: @PoliticalTicker
Brown's concerns come after CNN reported the Republican Party's Platform Committee had affirmed its opposition to abortion and support for a "human life amendment" in a meeting in Tampa, Florida, prior to the Republican National Convention next week.
The platform committee is charged with defining the Republican Party's stance on issues before the start of Monday's convention, where presumptive GOP nominee Mitt Romney and running mate Paul Ryan will officially be entered into nomination.
In a meeting Tuesday the group defined the Republican plank on abortion as this:
"Faithful to the 'self-evident' truths enshrined in the Declaration of Independence, we assert the sanctity of human life and affirm that the unborn child has a fundamental individual right to life which cannot be infringed," the platform language said. "We support a human life amendment to the Constitution and endorse legislation to make clear that the Fourteenth Amendment's protections apply to unborn children."
The stance will be finalized by the committee prior to the convention.
In the letter sent to RNC chairman Reince Priebus and also released to reporters, Brown urged Priebus to reconsider the draft language on the issue of abortion to reflect a broader portion of the party.
"If we are to grow and succeed in all parts of this great nation, we must be a 'big-tent' party," Brown wrote. "There are people of goodwill on both sides of the abortion issue, and we need to send a message to voters that there is room in the Republican Party for differing perspectives."
Brown concluded by writing, "I hope you and the platform committee will recognize this reality as you finalize this year's Platform document."
Brown, who is pro-abortion rights, argued the party should grant the same concessions to Republicans like himself as it does to those who oppose abortion, also noting that the GOP platform does not serve as a guide to every Republican in the party.
Brown is locked in a high-profile race to defend his Senate seat from rival Democrat Elizabeth Warren in Massachusetts - a state with a deeply liberal voting track on social issues.
Warren, a rising star in the Democratic Party, is slated to speak in a headlining role at the Democratic National Convention beginning September 4 in Charlotte, North Carolina.
In a tough week for Republicans on social issues, Rep. Todd Akin from Missouri made controversial comments on abortion, claiming that in cases that he referred to as "legitimate rape" the female body has ways to reject the pregnancy.
Brown was among the first in a host of Republicans, including Romney, to condemn Akin's remarks and call for the Senate candidate to step down from his position as the state's Republican nominee.
Akin has repeatedly refused to step aside despite a growing Republican voice claiming he would harm the party if he remains Missouri's GOP candidate facing rival Democratic Sen. Claire McCaskill in the general election.
Republicans are vying to gain control of the Democratic-controlled Senate come November. Akin's newly-found vulnerability puts these chances at stake in an U.S. Senate election previously thought to be a likely take-back for the Republican Party.
–CNN Political Reporter Peter Hamby contributed to this report.
– Check out the CNN Electoral Map and Calculator and game out your own strategy for November.