Sen. Bernie Sanders (I-Vt.) on Sunday redoubled his efforts to ensure that despite his loss to presumptive Democratic presidential nominee Hillary Clinton, the legacy of his progressive campaign will endure in the party's official platform.

Sanders, who has yet to drop out of the race and formally endorse Clinton, told CNN that his campaign made "very, very important victories" in inserting aspects of its policy agenda into the first draft of the platform. But he is determined to make a bigger mark.

"We have made some good gains," he said. "We have more to do."

Lucas Jackson/Reuters

Over the weekend, members of the Democratic Party's platform committee met in St. Louis to lay out the groundwork for the official policy agenda that party members will adopt at next month's convention in Philadelphia. Making the cut were several of Sanders' proposals, including a $15 minimum wage, the expansion of Social Security and stricter sanctions for Wall Street fraud, according to The Associated Press.

But the Vermont senator fell short in getting the broader hallmarks of his campaign into the draft -- policies such as building a single-payer health care system, rejecting the Trans-Pacific Partnership and taking a stronger stance on climate change by taxing carbon emissions and banning fracking.

Since Clinton sealed up the nomination in early June, Sanders' chief objective has been advocating for the inclusion of his progressive policy agenda in the platform.

In May, Democratic officials allowed him to name five of the platform committee's 15 members, with Clinton getting six and DNC chair Debbie Wasserman Schultz getting four. It was a concession to Sanders' campaign, since typically, the DNC chair appoints all of the members.

Sanders said on Sunday that he is determined to press on and reiterated his vow to take his campaign to the convention.

"We lost some very important fights. We're going to take that fight to Orlando, where the entire committee meets in two weeks," he said. "And if we don't succeed there, then we'll certainly take it to the floor of the Democratic convention."

On Friday, Sanders affirmed that he will vote for Clinton in November and will work to make sure she defeats presumptive GOP nominee Donald Trump. But he is not yet prepared to endorse her until she adopts more of his progressive policy positions.

"I hope very much that Secretary Clinton understands that not only is it good public policy, it's the right thing to do," he said on Sunday. "It is good politics to begin to move in that direction."