As an MLA Marc served as a Parliamentary Secretary for independent schools and was a member of the ‘Experience the Fraser’ steering committee, which was a trails and tourism project.

In 2019, Marc ran again in the federal election for the Conservative Party, this time winning and beating out the Liberal candidate Dan Ruimy by over 3000 votes.

While running in the 2009 British Columbia general election, an email written to a colleague from 1996 while Dalton was a schoolteacher was released by the NDP due to "homophobic comments", according to MLA Spencer Herbert.

[3] The email was a response to concerns over overreach in proposed policy changes to address bullying in which Dalton wrote: "I am not against homosexuals as people, but I do not support their lifestyle choices.

[5] In his capacity as Member of Parliament for Pitt Meadows - Maple Ridge, Dalton crafted a tweet met with controversy during the COVID-19 pandemic in Canada on April 13, 2020.

[6] In his post, Dalton stated regarding seniors, "Most deaths are in care homes where average life expectancy is 2 yrs & 65% usually pass in the 1st yr. Time to start moving Canada back to work?"

When questioned about the incident by media organizations, Dalton's office responded with the following, "Our thoughts and prayers are with the hundreds of Canadians who have lost loved ones because of COVID-19.

On January 3, 2020, as Member of Parliament for Pitt Meadows - Maple Ridge, Dalton retweeted an opinion column from The Washington Examiner on Twitter titled, "The transgender movement’s message for girls: Your privacy concerns are bigotry" "[7] Dalton defended his re-posting of the article stating he's not pushing the issue aggressively, but spoke about it previously when he was MLA.

[8] On June 22, 2021, Dalton along with 61 other Conservative caucus members and one independent voted against Bill C-6, An Act to amend the Criminal Code (conversion therapy).

On numerous occasions in the 44th Parliament, Dalton has spoken in the House of Commons to contest and censure the carbon tax introduced by the Liberal Government in 2018.