Sen. Pat Toomey (R., Pa.) raced across Pennsylvania Monday, with six stops scheduled in a bid to fend off a stiff challenge from Democrat Katie McGinty and, perhaps, strike a major blow for Republicans trying to hold onto the Senate.

McGinty, meanwhile, is joining the biggest names in the Democratic party - and two musical superstars - as party leaders try to not only win the White House, but also secure Democratic control in one chamber of Congress.

She joined Hillary Clinton early Monday for a rally in Pittsburgh, and is slated Monday night to take part in a marquee event on Independence Mall with the Democratic presidential candidate, President Obama, first lady Michelle Obama, Clinton's husband Bill and daughter Chelsea, Jon Bon Jovi, and Bruce Springsteen.

Her campaign also released a video Monday featuring President Obama re-affirming his endorsement of McGinty, hoping to counter Toomey's recent attempts to latch onto the president's one-time praise of the Republican senator.

Pennsylvania is one of a handful of races likely to determine control of the Senate and was looking too-close-to-call hours hours before voting booths open. Recent public polls suggest a small lead for McGinty, but Toomey has said his campaign data shows a "dead heat."

Toomey planned to hit Philadelphia, Bethlehem, Johnstown and several other locations Monday. He also appears poised to head to the voting booth himself Tuesday morning - near his Allentown-area home - without telling constituents whom he will support for president. McGinty has made his refusal to take a firm stand her key attack point for weeks.

McGinty's public schedule over the past week has consisted almost entirely of big rallies with party luminaries such as Clinton and Vice President Biden, events that have left little opportunity for interactions with reporters.

Her campaign did not make her available for an interview requested Saturday, and on Monday morning anchors on Philadelphia's Fox television affiliate said she had canceled a planned appearance there last week, and declined to reschedule. McGinty's campaign had mocked Toomey for his recent interview on the network, in which he repeatedly dodged questions about whether he would endorse Republican presidential nominee Donald Trump. A spokesman said she had to cancel Monday's Fox appearance in order to join Clinton's rally in Pittsburgh.

McGinty has invited some media outlets, including the Inquirer, to some recent appearances, and her aides have argued that she has been transparent and accessible throughout the campaign.

Meanwhile, they have promoted events - including two Monday - featuring other elected officials holding press conferences on McGinty's behalf, without the candidate present. She'll vote Tuesday in Wayne, and end the day at Democratic Party gathering in Philadelphia. Toomey's election-night party is near his home in Lehigh County.

The contrasting events Monday from Toomey and McGinty reflect their very different postures toward the top of the Democratic and Republican tickets, and mark the end of a caustic campaign that featured a deluge of attack ads through the race's final days - and that broke spending records, surpassing $155 million, according to the non-partisan Center for Responsive Politics.

Toomey, needing to win over swing voters in a state that tilts blue in presidential election years, has recently tried to link himself to top Democrats, including Obama, even as he has kept his distance from Trump.

He has run a television ad in Philadelphia and Pittsburgh featuring Obama's praise in 2013 for his bill on background checks for gun purchases, even while sharply opposing the president most topics.

At a campaign stop Saturday, for example, Toomey blamed "Washington" for a "pathetic" economic recovery - without mentioning Obama by name.

Toomey's campaign is hoping that a strong get-out-the-vote effort targeting a mix of cross-over voters and reliable conservatives can overcome Democrats' voter registration advantage.

Obama, however, said in his video Monday, "I want to make sure there is no confusion - I strongly support Katie McGinty for U.S. Senate."

McGinty, Gov. Wolf's former chief of staff, is hoping to ride a surge of Democratic enthusiasm to the Senate. Top party figures have urged the Democratic faithful to support not just Clinton, but McGinty as well.