Sen. Dianne Feinstein Dianne Emiel FeinsteinBiden leads Trump by 12 points among Catholic voters: poll Names to watch as Trump picks Ginsburg replacement on Supreme Court McConnell says Trump nominee to replace Ginsburg will get Senate vote MORE, the top Democrat on the Senate Judiciary Committee, is asking former Trump campaign aides to provide additional information on their Russian contacts during the 2016 presidential race.

The California lawmaker on Tuesday sent letters to Carter Page, Sam Clovis, Walid Phares and J.D. Gordon — all former Trump campaign officials who have come under scrutiny for connections to Moscow.

The signature of the Judiciary panel's chairman, Sen. Chuck Grassley Charles (Chuck) Ernest GrassleyGardner signals support for taking up Supreme Court nominee this year Grassley, Ernst pledge to 'evaluate' Trump's Supreme Court nominee McConnell digs in on vow to fill Ginsburg's Supreme Court seat MORE (R-Iowa), is notably missing from Feinstein's letters.

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In her letter to Page, she asks the former campaign foreign policy aide to turn over "all documents" related to his trips to Russia in July 2016 and December 2016, his communications with key Kremlin officials and businessmen starting in 2015, “all communications” with other Trump campaign officials who are under scrutiny," and any materials related to the Republican National Committee's stance toward Ukraine and Russia.

Feinstein's interest in Page's trips to Russia come after the House Intelligence Committee released transcripts of Page's testimony before their panel earlier this month. During his testimony, Page told lawmakers that he had at one point indicated to Gordon and Phares over email that then-candidate Donald Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE could make a trip to Russia during the campaign.

Page, who has previously testified before the Senate Judiciary Committee, captured the interest of lawmakers probing Russian interference in the election because of his 2016 Moscow trip as well as his appearance in a dossier of opposition research against Trump. The controversial set of memos, compiled by a former British intelligence officer, allege connections between the Trump campaign and the Kremlin.

Feinstein sought similar information from Clovis, who served as chief policy adviser for the Trump campaign, but also requested that he share all and any record related to “efforts to obtain or share ‘hacked emails’ ” from the Democratic National Committee, Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE campaign chairman John Podesta and any other electronic records from the Democratic candidate and her campaign.

Clovis came under fire in late October after documents from March revealed that he encouraged a young Trump campaign aide, George Papadopoulos, to meet with Russian officials in an effort to help improve the relations between Moscow and the campaign.

Papadopoulos pleaded guilty to lying to federal investigators about his contacts with Russia in early October.

Feinstein similarly requested that Gordon, who ran the campaign's foreign policy advisory team, and Phares, another foreign policy adviser on the Trump campaign, turn over "documents related to Russian contacts and the Republican Party’s position on Ukraine."

The Democratic senator asked that Clovis, Phares and Gordon appear before the committee for an interview as part of the ongoing probe.

Her statement on issuing the letters noted that "additional requests are expected to be sent in the coming weeks."

Trump as well as his former aides have denied colluding with Russians during the election.