But there's another delegation from the U.S. at the summit — a group of elected officials, businesses, universities, and nonprofits, all of whom are committed to meeting America's promises under the agreement — even without the administration's help.
Trump announced his intention to withdraw from the international climate deal in a Rose Garden speech in June, saying "I was elected to represent the citizens of Pittsburgh, not Paris".
Pittsburgh Mayor Bill Peduto is one of the attendees in Germany and has signed on to support the Paris deal.
The State Department formally notified the UN in August that the U.S. intends to withdraw from the agreement. However, because of the agreement’s legal structure, the earliest withdrawal can take place is November 2020 – right as Trump seeks re-election.
"If we could get a more favorable deal for American businesses, American workers and taxpayers, then we will look at that. But we continue to go forward with the plan of pulling out of the Paris accords," Nauert said last Tuesday.
But the White House said the delegation is not planning any negotiations on a better deal at COP23.
"We don't plan to talk about what those options could be," a White House official told reporters on a conference call. "I don't anticipate having delegations approach us and really try to get into that kind of discussion."
The administration has yet to provide any details of what a "more favorable deal" would look like or moved forward on any negotiations.
A White House official said the administration's position has not changed and they have no plans to discuss options that would lead to the U.S. remaining in the Paris deal. The official said administration officials are participating in events that aren't geared toward discussing the deal.
Who is representing the U.S.?
The highest level American official attending on behalf of the U.S. government was originally Under Secretary of State for Political Affairs Tom Shannon but the State Dept. announced on Tuesday that due to a family emergency, Shannon would be replaced by Acting Assistant Secretary of State for Oceans and International Environmental and Scientific Affairs Judith Garber.
The official delegation has been criticized for focusing on the role of fossil fuels and coal at this climate change summit. Research shows that emissions from burning fossil fuel contribute to warming temperatures.
Protesters from environmental advocacy groups disrupted a U.S. government event Monday with the U.S. Energy Association on "the critical role of fossil fuels," turning their backs to the panel and singing a rendition of "Proud to Be an American" for several minutes and then walking out.
"I think that this panel is only controversial if we choose to bury our heads in the sand and ignore the realities of the global energy system," Banks said at the beginning of the panel.
Banks laughed during the protest and joked that the "singing is pretty good."
The U.S. registered 49 people to attend the convention. That includes people from the State Dept., agencies like the Dept. of Energy, Treasury, USDA, and EPA, as well as a five senators and some congressional staff. In comparison the United Kingdom registered 45 people, China registered 83 people, and Canada registered 161.
While the U.S. delegation is present and meeting with other delegations there is reportedly no booth for the official delegation in the main pavilion. The unofficial delegation does have one it calls the U.S. Climate Action Center and has been hosting events there throughout the conference.
The alternative delegation has adopted the tagline "We Are Still In" and represents more than 2,500 leaders from state and local governments, private companies, and universities, according to its website. Democratic members of Congress also attended and participated in events about how the U.S. is working to meet the goals of the Paris agreement but they are also listed as part of the official delegation.
In total 20 states, 110 cities, and over 1,400 business from the U.S. have adopted targets to reduce greenhouse gas emissions, according to their report.
Rhode Island Sen. Sheldon Whitehouse, a Democrat, said no Republicans joined them, even though they had plenty of notice about the trip.
"The death grip of the fossil fuel industry on the Republican party precludes their participation in events like this without dire consequences to them and so therefore regrettably we are not a bipartisan delegation," Whitehouse said on a call with reporters.
Sen. Ben Cardin said Republicans are interested in their conversations at the summit and he will be reporting back to his colleagues on the foreign relations committee.
Most of the elected officials in the unofficial delegation are Democrats but there is at least one Republican, Mayor Jim Brainard of Carmel, Indiana.
One concern: Will the U.S. be left behind?
One reason members of the alternative American delegation said they felt it was important to attend was so the U.S. wouldn't be left behind as other countries continue to work together on climate issues. Chinese President Xi Jinping recently got a standing ovation for saying the world must act on climate change in his speech at an economic conference for Asian countries. Trump did not mention the issue of climate change in his speech at the same event.
One of the questions being discussed at COP23 is whether developing countries have to follow the same timelines as the rest of the world — an issue particularly important for the U.S. as it seeks to hold countries like China and India accountable for their share of greenhouse gas emissions.
"One of our concerns is that China may very well have a bigger role to play here at COP23 as a result of the United States not being as focused on this conference as we should be because of President Trump's comments," Sen. Ben Cardin, D-Md., said on a call with reporters last week.
There have also been questions about whether the U.S. is becoming more isolated after the delegation from Syria announced at the summit last week that they would sign on to the agreement, leaving the U.S. the only country opposed to the deal.
Nauert denied that this left the U.S. isolated, calling it "ironic" that Syria would say it cares about climate and carbon dioxide emissions.
"If the Government of Syria cared so much about what was put in the air, then it wouldn't be gassing its own people," Nauert said, referencing the regime's chemical gas attacks that have killed dozens of civilians in Syria, according to the UN.
But Trump's stance on the issue is having an effect on the world stage.
French President Emmanuel Macron is hosting a climate summit in December with 100 world leaders. French authorities told the Associated Press that President Trump is not invited, saying the leaders invited are "especially committed" to the Paris agreement. An invitation will be sent to the U.S. "at a diplomatic level," the official told the AP, but a State Dept. official did not respond when asked if the U.S. would send a delegation to that summit.
Leaders from Canada and Mexico released a joint statement from North American climate leaders on Monday, saying they will work with a coalition of U.S. governors. The statement did not mention the U.S. federal government.
The statement says the organizers plan a dialogue between the invited leaders and will discuss their shared goals at a summit in California in September. Canada's environmental minister posted a photo with California Gov. Jerry Brown and Washington Gov. Jay Inslee at the announcement.
More high-ranking officials are expected to attend the summit this week for negotiations about how the Paris agreement will be implemented.
ABC News' Jordyn Phelps contributed to this report.