The White House staffer killed Saturday while bicycling in a charity event was remembered by his pregnant widow for the ever-present twinkle in his eye, and by President Obama for his "brilliant mind, a big heart, and an insatiable desire to give back."

Jacob Thomas "Jake" Brewer, 34, a senior policy advisor in the White House Office of Science and Technology, was killed when he lost control of his bike at a sharp curve during the 150-mile Ride to Conquer Cancer fundraiser. His bike crossed a double yellow line and hit an oncoming vehicle, police said.

His heartbroken wife, Fox News contributor Mary Katharine Ham, said the pair, whose daughter is named Georgia, was looking forward to the birth of their second child.

"Simply put, Jake was one of the best."

- President Obama

"I don't have to tell most of you how wonderful he was," Ham wrote on Instagram. "It was self-evident. His life was his testimony, and it was powerful and tender and fierce, with an ever-present twinkle in the eye. I will miss him forever, even more than I can know right now."

Brewer's  mother, Lori Brewer Collins, said Brewer was taking part in the ride because of a close friend who was a cancer patient.

"[He] lived life large and tended to live life for other people,” Collins said.

Before joining the White House staff as an adviser to U.S. Chief Technology Officer Megan Smith, Brewer worked at Change.org and co-founded Define American. 

He was also a triathlete and a photographer. Ham, editor-in-chief of the right-wing political blog Hot Air, a contributing editor to Town Hall Magazine and a frequent guest on Fox News programs, lovingly referred to him on social media as "my outdoorsman."

President Obama said the White House suffered a loss with Brewer's tragic death. 

"Simply put, Jake was one of the best," President Obama said in a statement. "Armed with a brilliant mind, a big heart, and an insatiable desire to give back, Jake devoted his life to empowering people and making government work better for them. He worked to give citizens a louder voice in our society. He engaged our striving immigrants. He pushed for more transparency in our democracy. And he sought to expand opportunity for all."

Friends and family launched GoFundMe page with the goal of raising $200,000 for the education of the couple's two children.

"I will miss him forever, even more than I can know right now," Ham wrote on Instagram. "No arms can be her father's, but my daughter is surrounded by her very favorite people and all the hugs she could imagine."