All eyes are on the Democrats in the 2018 midterm elections as they try to take back control of the House and Senate.

In the House, Republicans hold a 43-seat majority over Democrats heading into the midterm elections. If Democrats do gain a majority, they will then be in control of House committees — and could thwart President Trump and the GOP’s legislative agenda.

In the Senate, Republicans only have a two-seat majority.

The 111th Congress, from 2009 to 2011, was the last time Democrats controlled both the House and Senate.

Read on for three things Democrats could impact if they gain control of Congress.

Russia probe

If Democrats regain a House majority, expect them to forge ahead with more probes into Russian interference in the 2016 presidential election and potential collusion with the Trump campaign.

The Republican-led Intelligence Committee has already closed its investigation into Russian meddling without finding evidence of collusion. But Democrats have charged the GOP committee members turned a blind eye to critical witnesses and evidence during the probe.

Texas Rep. Joaquin Castro, a member of the Intelligence Committee, previously told The Hill his party would quickly move to reopen the Russia investigation.

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“I know that the president thinks the entire investigation was a witch hunt, but we ought to have a fair process where we at least subpoena people and verify what was told to us,” Castro said.

Democrats are expected to call back key witnesses, look into Twitter messages between Donald Trump Jr. and WikiLeaks and allow public hearings with top Trump officials.

Trump’s taxes

Democrats could also flood the Trump administration with other investigations — such as seeking the president’s long-hidden tax returns — this time, armed with subpoena power.

Rep. Steny Hoyer, D-Md., has promised committees will “make sure the president is not operating on his own benefit as opposed to the public’s benefit.”

As for impeachment proceedings, top Democrats, such as House Minority Leader Nancy Pelosi, have primarily stayed away from discussing a strategy. But Special Counsel Robert Mueller’s findings from his Russia probe could always change that.

“I think an impeachment, to use that word, is very divisive,” Pelosi has said. “That isn’t a path that I would like to go down.”

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But Democrats who want an impeachment have urged the party to investigate Trump and build a case before attempting to remove him from office.

“What we want to say is, ‘Look we should have this information.’ We will see where it all leads,” Rep. Pramila Jayapal, a Democratic member of the House Judiciary Committee, told McClatchy. “I’m one of the people who believe we should be having a debate on impeachment, but that’s a political act. We have to build that case.”

Rep. Al Green, D-Texas, has repeatedly tried to file articles of impeachment against Trump but House Democrats have voted against them.

Nominations

There has been a high turnover rate of officials in the Trump administration, including his Cabinet.

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Trump's already had difficulties pushing through some of his Cabinet picks, and a Democrat-controlled Senate could further stymie efforts to replace anyone who leaves the administration in the coming years.

The same could be true if there’s another opening on the Supreme Court. Justice Brett Kavanaugh’s confirmation earlier this year was airtight after a historically rancorous debate — even with Republicans in control.

Fox News' Samuel Chamberlain and The Associated Press contributed to this report.