US Midterm Elections History: From 1866 to 1994 to 2018 – The polls that changed the course of American presidential power

The 2026 US midterm elections have brought a big change in Washington politics. The Democratic Party has won a majority of seats in both the House of Representatives and the Senate, and hence the sitting US President, Donald Trump, will have an opposition-led Congress in his last two years in office. However, this is not the first time that the midterm elections have made such a change during the reign of a sitting president.

There are several American midterm elections whose results were characterised by changes of such a nature.

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The three major elections that marked an important shift in presidential powers.

It started in 1866, when Congress clashed with President Andrew Johnson regarding the issue of Reconstruction; then in 1994, when Republicans succeeded in ending the long reign of Democrats in Congress under the Bill Clinton presidency; and finally in 2018, when Democrats won the House in the Donald Trump era.

1866: Andrew Johnson's clash with Congress changed Reconstruction

The midterm elections of 1866 occurred at a time when America was at one of its most turbulent chapters in history.

First, the Civil War had concluded in 1865, and President Abraham Lincoln had been assassinated, leaving Vice President Andrew Johnson as President. The key issue surrounding politics was the process of re-admitting the South into the Union and the rights that former slaves would have.

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President Johnson favoured a relatively gentle approach to the South.

The Republican Party in Congress, especially the Radical Republicans, pushed for strong protection of freed blacks from the Federal government and tough terms in re-admitting the South.

This led to a showdown between Johnson and Congress since Johnson vetoed laws approved by Congress. The result of the election in November of 1866 was a decisive victory for the Republicans against Johnson.

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However, the implications went beyond the election of 1866 itself.

Congress enacted the Reconstruction Acts in 1867, imposing military rule on large parts of the former Confederacy while the Southern states were seeking admission back into the Union.

This was a time when the 14th Amendment, providing for citizenship and due process of law, was ratified.

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In the end, the confrontation came to Johnson’s very presidency.

Johnson was impeached by the House in 1868 but narrowly avoided conviction by the Senate vote. It served as an example of how mid-term elections gave Congress the strength to confront the President himself.

1994: The Republican Revolution ended a 40-year Democratic hold

Over 130 years later, another midterm election shifted the dynamics of political power in Washington.

During the elections of November 1994, Republicans took control of both chambers of Congress, ending the Democrats' longtime hold on the House of Representatives and capturing the Senate too.

President Bill Clinton had come into office in 1993 with plans for a sweeping domestic agenda.

Yet his attempt at health care reform had fallen flat, and some of his other policies were unpopular among conservatives.

The Republicans, under the leadership of Speaker-designate Newt Gingrich in the House, made the election about the future of the Clinton presidency.

The Republican campaign was based on the "Contract with America," a set of legislative proposals which included tax cuts, welfare reform, a balanced budget amendment, and other congressional reforms. More than 300 Republican House nominees signed the document before the election.

As a result, the party was able to get 54 seats in the House of Representatives and a majority that they had not enjoyed since 1954. The Republicans also managed to capture the Senate, gaining leverage over legislation, committees and setting the congressional agenda.

Newt Gingrich became the Speaker of the House of Representatives in January 1995 when the new Congress started its work.

Clinton was not impeached from the presidency, but his power to pass laws changed dramatically; now he needed to deal with the Congress controlled by the Republicans, and the confrontation over budgets and federal policy became one of the distinctive features of his presidency.

It became clear that the 1994 elections laid a foundation for the new style of Congress.

2018: Democrats took the House and opened a new chapter of oversight

Another congressional defeat for Donald Trump came about during the 2018 midterm elections.

The Republicans were able to retain control of the Senate, but the Democrats added 41 new members to their representation in the House, thus gaining control of the House for the first time since 2010.

This came after two years of heated discussion regarding Donald Trump's presidency, which involved issues such as immigration, health care, the administration's policies and interference by Russians in the 2016 elections.

The opposition to President Trump was the major theme in many of the campaign races of the Democratic Party, and the suburbs had a significant influence on the results.

After the Democratic Party assumed control of the House in January 2019, they gained control of the committees in the House.

The most important event would be the impeachment of Trump by the House in December 2019 for abuse of power involving Ukraine. He was acquitted by the Senate in February 2020. The House impeached him a second time following the January 6, 2021 attack on the US Capitol; he was again acquitted.

It is clear that the election of 2018 provided an illustration of the importance of winning at least one chamber in order to have significant oversight powers.

Although the Democrats could not control the entire process, they could investigate the administration and bring its policies up for debate. The record of the US House of Representatives reflects the gain of 41 seats by the Democrats.

What the 2026 result could mean for Trump

The historical precedents provide different models that can apply to the political predicament facing Trump.

The 1866 election provided a model on how a Congress emboldened by its victory could challenge a president on national issues.

The 1994 elections provided an example of how the opposition party could alter the congressional agenda. The 2018 elections provided an example of how a House majority can conduct investigations leading to impeachment.

The 2026 result is not an exact repeat of any of these races. Democrats have won both houses, according to the Associated Press, putting them in charge of more of Congress than Democrats did in 2018.

The new Congress will be expected to meet in January 2027.

The coming steps will depend upon how the Democratic leadership handles their majorities, if they can hold together their party, and how the White House reacts.

From historical experience, the loss of Congress will not necessarily mean that the president's program and presidency are over. It will mean that the terms of political discussion in Washington are no longer set by them.