Democratic presidential hopeful Steve Bullock Steve BullockMcConnell locks down key GOP votes in Supreme Court fight Senate Democrats demand White House fire controversial head of public lands agency Pence seeks to boost Daines in critical Montana Senate race MORE said Wednesday that increasing transparency in campaign finance laws is key to addressing issues like climate change and gun violence.

Speaking after an event at the National Press Club on Wednesday in Washington, D.C., Bullock said battling "dark money" had been the fight of his career.

“Some people say that this is a fringe issue but when we talk about climate change, when we talk a about gun safety and gun violence, when we talk about economic inequality, when we talk about prescription drug prices, so much of it is we don’t actually address the corrupted influenced of money in the system that drives this city,” he said.

Bullock, a longshot presidential hopeful, has made fighting dark money a central issue of his campaign.

As Montana's governor, Bullock has worked to crack down on dark money in the state. In 2015, he signed a bipartisan bill requiring anonymous dark money groups to disclose how they are spending money in state-wide races.

Bullock has been polling around less than 1 percent support for much of the 2020 race. Still, he was able to qualify for last week's second Democratic presidential debates, after failing to do so the first time around. Speaking first during last week's debate, Bullock knocked liberal heavyweights Sens. Elizabeth Warren Elizabeth WarrenHillicon Valley: Subpoenas for Facebook, Google and Twitter on the cards | Wray rebuffs mail-in voting conspiracies | Reps. raise mass surveillance concerns On The Money: Anxious Democrats push for vote on COVID-19 aid | Pelosi, Mnuchin ready to restart talks | Weekly jobless claims increase | Senate treads close to shutdown deadline Democratic senators ask inspector general to investigate IRS use of location tracking service MORE (D-Mass) and Bernie Sanders Bernie SandersThe Hill's Campaign Report: Trump faces backlash after not committing to peaceful transition of power Bernie Sanders: 'This is an election between Donald Trump and democracy' The Hill's 12:30 Report: Trump stokes fears over November election outcome MORE (I-Vt.) over what he characterized as their “wish-list economics.”

⁠—Tess Bonn