[4] He ran in the 2024 Democratic primary to succeed Annie Kuster in New Hampshire's 2nd congressional district; he was defeated by Maggie Goodlander.

[8] Previously, Van Ostern worked as vice president of Workforce Solutions[9] at Southern New Hampshire University.

Van Ostern was first elected to the Executive Council after campaigning on the importance of building passenger rail from Boston to central New Hampshire.

The New Hampshire Capitol Corridor rail project was halted by the Executive Council in 2011, but continued in 2013 after Van Ostern was elected.

Van Ostern publicly opposed Republican members of the Executive Council when they voted against funding family planning services at New Hampshire's Planned Parenthood health centers in both 2011 and 2015, and in 2015 he was awarded[14] the Champion of Choice award by NARAL Pro-Choice New Hampshire, the state's largest grassroots organization dedicated solely to reproductive rights.

In October 2014, 1,700 workers at Fairpoint Communications in New Hampshire, Maine, and Vermont went on strike after the company froze pensions, implemented pay reductions for new employees, and limited health care benefits.

Negotiations between the company and striking workers resumed on January 4, 2015[17] and the contract was passed unanimously on the Executive Council later that month.

[22] On March 28, 2024, Van Ostern announced that he would run for New Hampshire’s 2nd congressional district in the election that year to succeed retiring Representative Annie Kuster.