How to access WithdrawChecking() in LoginForm inside MainTransactionForm

public partial class MainTransactionForm : Form
{
    public MainTransactionForm()
    {
        InitializeComponent();
    }
    public LoginForm loginForm = new LoginForm();
    private void MainTransactionForm_Load(object sender, EventArgs e)
    {
        this.Width = 803;
        this.Height = 631;
        lblUsername.Text = loginForm.GetUsername();
        lblUserType.Text = loginForm.GetUserType();
        lblBalance.Text = loginForm.GetBalance();
    }
}