Senators Ruben Gallego (D-AZ) and Seth Moulton (D-MA) criticized Trump's position on the military and veterans.
According to Gallego, Trump has done little to help veterans, and that Trump had fulfilled a promises to give money to veterans only after pressure from the media.
Gallego suggested that Trump's comparison of his attendance at a New York military academy, as being similar to that of serving in the armed forces, was wrong.
The Arizona Senator also called Trump's questioning of the status of Senator John McCain (R-AZ) as a war hero "absolutely shameful."
"It really just blows my mind how he can be considered legitimate to become president of the United States," remarked Gallego.
"He attacked those of us who served in Iraq by broadly accusing soldiers of stealing reconstruction funds," said Moulton. "We've become sadly accustomed to Donald Trump's outrageous statements."
Moulton has called Trump's praise of the Saddam Hussein "unbelievably insulting." While Trump said last week that the former Iraqi leader "was good at killing terrorists," Moulton countered that the deceased Iraqi leader was "good at nothing other than being a dictator and gassing his own people."
"He clearly doesn't know anything about fighting terrorism," said Moulton, referring to Trump, also criticizing the real-estate speculator's comments last month in questioning whether US soldiers were responsible, in part, for reconstruction funds being lost during the Iraq War. According to a Trump aide, the candidate was referring to Iraqi soldiers.
The criticism came just before Trump's speech Monday on improving social networks for veterans, including allowing veterans to seek government-funded private medical care.