AUGUSTA – Maine elections officials expect a flood of paperwork this week as candidates for governor, Congress and the Legislature file the petitions needed to qualify for this June’s primaries.

Gathering petition signatures from registered voters is the first major hurdle for campaigns. Candidates seeking nominations from Maine’s four state-recognized parties – Republican, Democratic, Libertarian and Green Independent – face a Thursday deadline to submit petition signatures to Maine Secretary of State Matt Dunlap’s office in order to participate in the June 12th primaries. The threshold for gubernatorial and U.S. Senate candidates is 2,000 signatures while candidates for U.S. House must collect at least 1,000 signatures.

On Monday, Betsy Sweet of Hallowell and Attorney General Janet Mills of Farmington became the first two Democrats to qualify for their party’s primary in the governor’s race. With 10 Democrats still listed as having “active” campaigns, they should have plenty of company on the ballot, although the field is expected to shrink somewhat by Thursday evening’s deadline.

Kristen Muszynski, spokeswoman for Dunlap’s office, said staff encourage campaigns to make appointments before dropping off petition signatures because they typically take a few hours to review and certify.

Two more Democratic hopefuls for governor – former House Speaker Mark Eves of North Berwick and Sen. Mark Dion of Portland – have made appointments to file their petitions on Wednesday, Muszynski said. A spokeswoman for Democrat Adam Cote of Sanford said he would also likely file Tuesday or Wednesday, depending on the snowstorm.

On the Republican side, former Health and Human Services Commissioner Mary Mayhew was also certified Monday to participate in her party’s gubernatorial primary. Mayhew will join two other Republicans – Senate President Mike Thibodeau of Winterport and Senate Majority Leader Garrett Mason of Lisbon Falls – who had already qualified for the ballot before Monday.

Businessman Shawn Moody of Gorham had also made an appointment to submit his petition signatures on Wednesday, Muszynski said. The fifth Republican candidate for governor is House Minority Leader Rep. Kenneth Fredette of Newport.

The primary races for Maine’s three congressional races are also shaping up.

U.S. Rep. Bruce Poliquin, R-District 2, has qualified for his re-election bid and is expected to be unopposed in the Republican primary. As of Monday afternoon, two Democrats had qualified to seek the party’s nomination to challenge Poliquin: Assistant House Majority Leader Rep. Jared Golden of Lewiston and home builder Jonathan Fulford of Monroe.

U.S. Rep. Chellie Pingree, D-District 1, has also qualified for the ballot and is running unopposed in the Democratic primary.

In Maine’s Republican primary for U.S. Senate, state Sen. Eric Brakey of Auburn is scheduled to file his signatures on Wednesday while Max Linn of Ellsworth is slated to submit his on Thursday. They are vying to challenge incumbent U.S. Sen. Angus King, who as an independent has until June 1 to file at least 4,000 signatures to qualify for the November ballot.

Likewise, independent candidates for governor must submit 4,000 signatures by June 1.