I've seen a lot of complaints about the difficulty in getting funding for fusion research in the USA because so many people are invested, emotionally, politically, or monetarily, into the international fusion research programs. They see most any American fusion research as unnecessary, redundant, and a distraction. This is precisely the same complaints used by people opposing international fusion energy research. Sometimes it is not even a matter of funding, it's getting a license from the government to build the reactor.
There's reasons why American companies, universities, and so on want research in the USA. Sending people to work overseas is inconvenient and costly. It's also slow, because anything done has to please all the countries that are funding this program. People in the Department of Energy are certainly invested in keeping money flowing to ITER instead of domestic programs.
It's true that there is fusion research happening in the USA. What is also true is that the USA has been hobbling itself on doing more research because of international politics and lack of support by a certain political party, though this stance may have changed. The USA is falling behind on nuclear energy, fission and fusion, because the federal government has been hostile to it. Again mostly because of one major political party, and this may have changed or will change soon.
If any American university wants to do research on fusion then it may not get permission to go through with it unless it is framed as a pure physics program, not an energy program. The US Navy has funded nuclear energy research, again in fission and fusion, but they have to keep this small and quiet or the US Department of Energy will claim jurisdiction, take over the program, and then kill it. The DOE would do this by arguing that such research is redundant to international research programs they already fund.
I'm seeing the Department of Defense producing far more results in energy research than the Department of Energy. My guess is because the DOD has well defined goals in this research while the DOE does not. The DOD is funding research in nuclear power plants to propel warships as well as potentially power military bases. The DOD sees a need for alternative sources of fuel for everything from portable coffee pots and tent heaters to tanks and bombers. They fund programs in biomass fuels, hydrocarbon synthesis, and electric vehicles to this end. Because remote operating posts might not have access to any electrical grid, and even domestic bases could lose power from the grid in a natural disaster or war, they've been looking into solar and wind power.
What does the Department of Energy do? They spend a lot of money on ITER, which isn't likely to produce anything of value for decades. They spent money on a lot of electric car companies, solar panel companies, and so on that could not get private funding, because private investors could see them as frauds, highly risky, poorly managed, and almost always a failure.
The Department of Energy has no real incentive in solving our energy problems. That's because if they solve the problem then they have no reason to exist. The Department of Energy should disappear and all the facilities and people absorbed into other departments. Any nuclear power research could be split among the DOD (military power plants), TVA (federal power plants), and NRC (oversight on state and private power plants). Power from wind, water and sun would fall under Interior. Biomass fuels goes to Agriculture. Management of the electrical grid and other interstate trade of energy goes to Commerce. In other words, back to how things were before the Department of Energy existed, at least for the most part.
That's not likely to happen because any such proposal would be political suicide. The DOE has every incentive to NOT solve our energy problems but proposing to remove this disincentive by distributing the research they do to departments with a real incentive would be painted as a plan to put the nation at a disadvantage in energy research. The reality is different. The Department of Energy was created to remove the nation from dependence on foreign nations for energy, and we got there in spite of it, not because of it. If we, as a nation, lose this ability to produce all the energy we consume then my guess is it will be because of interference from the DOE.