Joe Biden's nominee for ambassador, Linda Thomas - Greenfield, vows to take a tougher line against China during her confirmation on Wednesday, exert influence over the multinational organization

Linda Thomas-Greenfield, President Joe Biden's nominee to be U.S. ambassador to the United Nations, faces her Senate confirmation hearing Wednesday, vowing to bring back "genuine, old-fashioned, people-to-people diplomacy," according to her prepared remarks obtained by ABC News.

U.S. Ambassador to the United Nations nominee Linda Thomas-Greenfield speaks at the Queen Theatre in Wilmington, Delaware. | Mark Makela/Getty Images

Thomas-Greenfield, a career ambassador who retired from the Foreign Service in 2017 as the top U.S. diplomat for Africa and former U.S. envoy to Liberia, will also promise a tougher line on China, according to her prepared testimony, as the Biden administration faces pressure from Republicans to take a hard line against Beijing and its growing global ambition.

"We know that China is working across the U.N. system to drive an authoritarian agenda that stands in opposition to the values of the institution," Thomas-Greenfield told lawmakers on the Senate Foreign Relations Committee.

"Their success depends on our continued withdrawal," she added. "That will not happen on my watch."

It was an effort to show she would be tough on China, while also expressing remorse for giving a speech at a Chinese-funded foundation based on a university campus in Savannah, Ga., in 2019.

In the speech, Thomas-Greenfield offered qualified optimism that the U.S. and China could both be positive influences in Africa. Her remarks became a contentious issue for some members of the committee.

That speech said Sen. Jim Risch of Idaho, the top Republican on the committee, "has become quite the buzz in these hallways in recent days."

If confirmed, Thomas-Greenfield, known affectionately by colleagues as "LTG," would be the second Black woman to serve as U.S. ambassador to the U.N. and a part of Biden's Cabinet. Biden again elevated the role to Cabinet-level after Trump removed it during his second envoy Kelly Craft's tenure, as it was under both Presidents Bush.

But she will face a grilling first by the Senate Foreign Relations Committee, where Republican senators are expected to raise China, Iran, the U.N. system, and other hot-button issues.

Thomas-Greenfield pledged to try to strengthen international relationships that frayed under the Trump administration, which withdrew from a number of UN bodies and often pursued a solo approach to diplomacy, according to Politico.

She also pledged to defend Israel at the United Nations, where the Middle East country is a frequent target of critical resolutions.

Thomas-Greenfield said she hoped that the Abraham Accords between a handful of Arab countries and Israel meant that Israel will have more support from its neighbors at the United Nations. Those accords, which are an effort to normalize the relationships between Israel and countries such as the United Arab Emirates, were unveiled under the Trump administration.

Sen. Ted Cruz, R-Texas, holds a copy of a 2019 speech by Linda Thomas-Greenfield that she delivered at the Chinese-government sponsored Confucius Institute at Savannah State University. Pool/Getty Images

According to NPR, democrats on the committee highlighted her life story, growing up in Louisiana, attending segregated schools, then going on to graduate from Louisiana State University prior to becoming one of the few Black women diplomats as to why colleagues should confirm her for the U.N. ambassador post.

"Ambassador Thomas-Greenfield has lived the ideals of our nation, even at a time when it was falling short of our founding ideals, and has spent her career blazing trails," Sen. Chris Coons, D-Del., said during the hearing.

Sen. Cory Booker, D-N.J., defended the now controversial speech, not for its content, but for Thomas-Greenfield's willingness to address a historically Black institution.

"The fact that you accepted an invitation from a Black college to give a speech, to me, shows you have the right priority list," Booker said, praising her as part of a generation of women breaking down barriers.

"Our State Department ranks are woefully lacking in African Americans," he added.

If confirmed, Thomas-Greenfield will represent the Biden administration at the U.N. during a period of renewed racial tensions in the United States. It would also mark her return to the foreign service after being pushed out during the Trump administration.

Prior to leaving diplomatic service in 2017, she oversaw the Bureau of African Affairs during the Obama administration. She previously served as director general of the foreign service as well as ambassador to Liberia.

President Biden has elevated the position of U.N. ambassador to cabinet level, giving another Black woman a prominent post within his administration.

In March, the U.S. will assume the presidency of the 15-member United Nations Security Council.

During her opening remarks before the committee, Thomas-Greenfield nodded to the four women who previously held the U.N. ambassador post, known as the U.S. permanent representative: Susan Rice, Nikki Haley, Kelly Craft and Samantha Power, Biden's pick to lead the U.S. Agency for International Development.

But it was the 1950 Nobel Peace Prize acceptance speech by Ralph Bunche, the legendary African American diplomat, that she quoted from during the hearing, calling the United Nations "the greatest peace organization ever dedicated to the salvation of mankind's future on earth."

Thomas-Greenfield took it a step further, adding to Bunche's remarks.

"But that's only true if America is leading the way," she said.

"When America shows up, when we are consistent and persistent, when we exert our influence in accordance to our values, the United Nations can be an indispensable institution for advancing peace, security and our collective well-being," she continued.

"If instead we walk away from the table and allow others to fill the void, the global community suffers and so do American interests."